https://earthwise.bgs.ac.uk/index.php?title=St._Abb%27s_Head_-_an_excursion&feed=atom&action=historySt. Abb's Head - an excursion - Revision history2024-03-29T15:11:10ZRevision history for this page on the wikiMediaWiki 1.41.0https://earthwise.bgs.ac.uk/index.php?title=St._Abb%27s_Head_-_an_excursion&diff=23174&oldid=prevScotfot at 21:47, 6 November 20152015-11-06T21:47:17Z<p></p>
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<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>'''By D.C.Greig. From Scottish Borders geology: an excursion guide edited by A.D. McAdam, E.N.K. Clarkson, P. Stone. Edinburgh : Scottish Academic Press (for [https://www.edinburghgeolsoc.org/ Edinburgh Geological Society]), 1972.'''</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>'''By D.C.Greig. From <ins style="font-weight: bold; text-decoration: none;">[[</ins>Scottish Borders geology: an excursion guide<ins style="font-weight: bold; text-decoration: none;">]] </ins>edited by A.D. McAdam, E.N.K. Clarkson, P. Stone. Edinburgh : Scottish Academic Press (for [https://www.edinburghgeolsoc.org/ Edinburgh Geological Society]), 1972.'''</div></td></tr>
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</table>Scotfothttps://earthwise.bgs.ac.uk/index.php?title=St._Abb%27s_Head_-_an_excursion&diff=22874&oldid=prevJenniferFindlay1 at 15:22, 27 October 20152015-10-27T15:22:52Z<p></p>
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<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>==== Introduction ====</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>==== Introduction ====</div></td></tr>
<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>The principal object of this excursion is to study the volcanic rocks of Lower Old Red Sandstone (Lower Devonian) age which form the peninsula of St Abb's Head, on the Berwickshire coast north of St Abb’s and Coldinghame. The excursion could occupy a full day, but as it does not cover a very extensive area it can conveniently be cut short as required. The complete circuit covers a distance of about 8 km, of which about 4 km is over hilly open pasture, 1 km over rough rocky seashore, and nearly 3 km on a surfaced hill-road. The steep grassy slopes above the precipitous cliffs of St Abb's Head demand sturdy boots. The excursion is affected by the state of the tide at only one or two localities, possibly requiring adjustments to the route </div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">[[File:P000813.jpg|thumb|300px|right|Oblique aerial view of St. Abb's from the east. Berwickshire. </ins>The <ins style="font-weight: bold; text-decoration: none;">rocks in the foreground are intrusive porphyrites and agglomerates. The rocks on the shore are intrusive porphyrites and unbedded agglomerates, probably within a volcanic vent, of Lower Old Red Sandstone age. Beyond the trees in middle distance the high ground is formed of Silurian greywackes and siltstones. The vent, while not clearly defined, is recognized as such by the chaotic distribution of igneous and pyroclastic rocks on the well-exposed shore and cliffs, and by the extensive occurrence of very coarse agglomerates unlike any of the bedded sequence of St. Abb's Head. P000813]]he </ins>principal object of this excursion is to study the volcanic rocks of Lower Old Red Sandstone (Lower Devonian) age which form the peninsula of St Abb's Head, on the Berwickshire coast north of St Abb’s and Coldinghame. The excursion could occupy a full day, but as it does not cover a very extensive area it can conveniently be cut short as required. The complete circuit covers a distance of about 8 km, of which about 4 km is over hilly open pasture, 1 km over rough rocky seashore, and nearly 3 km on a surfaced hill-road. The steep grassy slopes above the precipitous cliffs of St Abb's Head demand sturdy boots. The excursion is affected by the state of the tide at only one or two localities, possibly requiring adjustments to the route </div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>St Abbs lies 7 km south-east of Fast Castle and is reached by the B6438 road from Coldingham. The headland, just north of the village, is a National Nature Reserve, managed jointly by the National Trust for Scotland and the Scottish Wildlife Trust [https://www.nts.org.uk/Property/St-Abbs-Head-National-Nature-Reserve/Property-description NTS-SWT]. Car and coach parking are located beside the information centre and coffee shop at Northfield Farm (NT 913 674), limited car parking is also possible near the Lighthouse (NT 913 692). The excursion is described as starting and finishing at the information centre, where an illustrated guide to the Reserve and other literature are available. </div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>St Abbs lies 7 km south-east of Fast Castle and is reached by the B6438 road from Coldingham. The headland, just north of the village, is a National Nature Reserve, managed jointly by the National Trust for Scotland and the Scottish Wildlife Trust [https://www.nts.org.uk/Property/St-Abbs-Head-National-Nature-Reserve/Property-description NTS-SWT]. Car and coach parking are located beside the information centre and coffee shop at Northfield Farm (NT 913 674), limited car parking is also possible near the Lighthouse (NT 913 692). The excursion is described as starting and finishing at the information centre, where an illustrated guide to the Reserve and other literature are available. </div></td></tr>
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<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>[[File:StAbbsHeadExcursionMap.jpg|thumb|600px|right|St Abb's Head]]</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>[[File:StAbbsHeadExcursionMap.jpg|thumb|600px|right|St Abb's Head]]</div></td></tr>
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<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>==== 1. Northfield: Viewpoint ====</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>==== 1. Northfield: Viewpoint ====</div></td></tr>
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<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>==== 5. Horsecastle Bay: Agglomerate, Brecciated Lavas, Lamprophyre Dyke ====</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>==== 5. Horsecastle Bay: Agglomerate, Brecciated Lavas, Lamprophyre Dyke ====</div></td></tr>
<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>[[File:P005893.jpg|thumb|<del style="font-weight: bold; text-decoration: none;">200px</del>|right|St. Abb's Head, Horsecastle Bay. View N. Grits and lava. Bedded tuffaceous grits overlie massive lava in the foreground, and are overlain on the headland by a later flow with a clearly irregular base. Such interrelations of bedded grits are not uncommon in the predominantly lava sequence of St. Abb's Head. Lower Old Red Sandstone. [https://194.66.252.158/asset-bank/action/viewAsset?id=5142 P005893]]]</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>[[File:P005893.jpg|thumb|<ins style="font-weight: bold; text-decoration: none;">300px</ins>|right|St. Abb's Head, Horsecastle Bay. View N. Grits and lava. Bedded tuffaceous grits overlie massive lava in the foreground, and are overlain on the headland by a later flow with a clearly irregular base. Such interrelations of bedded grits are not uncommon in the predominantly lava sequence of St. Abb's Head. Lower Old Red Sandstone. [https://194.66.252.158/asset-bank/action/viewAsset?id=5142 P005893]]]</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>From Burnmouth Harbour follow H.W.M. for 200 m to a little embayment on the north side of the headland of Horse Castle, where the agglomeratic country rock is cut by 3-m dyke of highly micaceous lamprophyre. It follows a curved north-easterly course, is cut by faults, and has two thin offshoots on its south-eastern side. It could be the same intrusion as that noted earlier at White Heugh and on Bell Hill, and is the only minor intrusion so far recognised in the lava sequence. Most of the rock between Burnmouth Harbour and Horsecastle Bay is roughly bedded brecciated lava. Thin layers of unbroken lava are present, being clearly distinguishable on the stack of Horsecastle Rocks, and one at least 4.5m thick caps the cliffs at Horse Castle, near the lamprophyre dyke. Typical broken lava is well exposed on the south- eastern side of Horsecastle Bay, where many large tabulate or rounded fragments of lava lie parallel to the major bedding fractures. The rock is thought to result from the spasmodic solidification of lava during the continuing movement of the flow as a whole.</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>From Burnmouth Harbour follow H.W.M. for 200 m to a little embayment on the north side of the headland of Horse Castle, where the agglomeratic country rock is cut by 3-m dyke of highly micaceous lamprophyre. It follows a curved north-easterly course, is cut by faults, and has two thin offshoots on its south-eastern side. It could be the same intrusion as that noted earlier at White Heugh and on Bell Hill, and is the only minor intrusion so far recognised in the lava sequence. Most of the rock between Burnmouth Harbour and Horsecastle Bay is roughly bedded brecciated lava. Thin layers of unbroken lava are present, being clearly distinguishable on the stack of Horsecastle Rocks, and one at least 4.5m thick caps the cliffs at Horse Castle, near the lamprophyre dyke. Typical broken lava is well exposed on the south- eastern side of Horsecastle Bay, where many large tabulate or rounded fragments of lava lie parallel to the major bedding fractures. The rock is thought to result from the spasmodic solidification of lava during the continuing movement of the flow as a whole.</div></td></tr>
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<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>==== 8. Cauldron Cove: Faulted Grits and Lavas ====</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>==== 8. Cauldron Cove: Faulted Grits and Lavas ====</div></td></tr>
<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>Follow the base of Kirk Hill northwards and north-eastwards to regain the sea-cliffs at Cauldron Cove. On the south-east side of the cove 4.5 m of bedded tuffaceous grits form a crag at the top of a very steep grassy slope, close below the lava of Kirk Hill. Below these grits, beyond about 4.5 m of concealed strata, a further 18 m of thinly bedded grits are exposed, more massive towards their base, resting on massive lava. Keep well to the right in descending the steep grass here, to avoid the dangerous slopes overhanging the vertical cliffs which bound the inlet. The beds dip ESE at between 28 and 40°. This 27-m group of tuffaceous grits occupies the marked depression west of Kirk Hill, and can be traced to old workings at the south-eastern end of Mire Loch. Its postulated recurrence at Horsecastle Bay, despite the dip of the strata, is attributed to the effect of faults like that seen at the bay, which repeatedly step the beds upwards as they are followed down-dip. One or two of these faults may be recognised on the sea-cliffs of Kirk Hill. Cauldron Cove marks the line of a group of north-east faults, one of which, reversed and hading to south-east, coincides with a cave at the head of the inlet. The base of the 27- m grits is exposed on the south-east side of the fault; to north-west only higher beds of the grits are seen.</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">[[File:P005892.jpg|thumb|300px|left|St. Abb's Head, Cauldron Cove. View SW. Grits and lava. Bedded tuffaceous grit (c. 27 m. thick) dips to left and overlies massive lava (lower left). The lava appears to be thrust over bedded grits in right foreground. Lower Old Red Sandstone. P005892]]</ins>Follow the base of Kirk Hill northwards and north-eastwards to regain the sea-cliffs at Cauldron Cove. On the south-east side of the cove 4.5 m of bedded tuffaceous grits form a crag at the top of a very steep grassy slope, close below the lava of Kirk Hill. Below these grits, beyond about 4.5 m of concealed strata, a further 18 m of thinly bedded grits are exposed, more massive towards their base, resting on massive lava. Keep well to the right in descending the steep grass here, to avoid the dangerous slopes overhanging the vertical cliffs which bound the inlet. The beds dip ESE at between 28 and 40°. This 27-m group of tuffaceous grits occupies the marked depression west of Kirk Hill, and can be traced to old workings at the south-eastern end of Mire Loch. Its postulated recurrence at Horsecastle Bay, despite the dip of the strata, is attributed to the effect of faults like that seen at the bay, which repeatedly step the beds upwards as they are followed down-dip. One or two of these faults may be recognised on the sea-cliffs of Kirk Hill. Cauldron Cove marks the line of a group of north-east faults, one of which, reversed and hading to south-east, coincides with a cave at the head of the inlet. The base of the 27- m grits is exposed on the south-east side of the fault; to north-west only higher beds of the grits are seen.</div></td></tr>
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<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>==== 9. Lighthouse Cliffs: Lava-Tuff Topography ====</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>==== 9. Lighthouse Cliffs: Lava-Tuff Topography ====</div></td></tr>
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<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>==== 12. Pettico Wick: Silurian Greywackes and Shales ====</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>==== 12. Pettico Wick: Silurian Greywackes and Shales ====</div></td></tr>
<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>The little natural harbour of Pettico Wick straddles the St Abb's Head Fault. Lower Devonian lavas of the St Abb's Head outcrop form the steep north-eastern cliffs, whereas the rocks on the south-western side of the bay are clearly well-bedded sediments, greywackes and shaly siltstones of Silurian (Llandoverian) age, as seen in the narrow outcrop at locality 2. The exact position of the fault is obscured by superficial deposits, but its general line, along Mire Loch to south-east, is very clear. </div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">[[File:P000817.jpg|thumb|300px|right|Pettico Wick, St. Abb's. Looking westwards to Silurian cliffs. Berwickshire. The rocks are greywackes and siltstones of the Llandovery series folded by repeated broad flexures with an east-north-eastward trend. The complex syncline of Broadhaven Bay is well displayed on the left, the broad north-western limb continuing to the right, as the photograph suggests, across the two minor headlands. The foreground rocks are Lower Old Red Sandstone lavas of St. Abb's Head, separated from the greywackes by a north-west to south-east fault in the bay below. P000817]]</ins>The little natural harbour of Pettico Wick straddles the St Abb's Head Fault. Lower Devonian lavas of the St Abb's Head outcrop form the steep north-eastern cliffs, whereas the rocks on the south-western side of the bay are clearly well-bedded sediments, greywackes and shaly siltstones of Silurian (Llandoverian) age, as seen in the narrow outcrop at locality 2. The exact position of the fault is obscured by superficial deposits, but its general line, along Mire Loch to south-east, is very clear. </div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>At Pettico Wick the Silurian rocks are disposed in a complex multiple syncline with a horizontal north-easterly axis, best studied below half-tide. This syncline is typical of the many major folds of the Silurian outcrop, which extends on the coast effectively to Siccar Point and over a wide area inland to south-west. Graptolites have been collected from finer-grained bands on the descent to the beach, and just round the corner on the left near HWM. Sedimentation structures can be seen in places on the upper and lower surfaces of the greywackes, current-bedding is locally developed, and axial-plane cleavage is seen in some of the finer-grained rocks. </div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>At Pettico Wick the Silurian rocks are disposed in a complex multiple syncline with a horizontal north-easterly axis, best studied below half-tide. This syncline is typical of the many major folds of the Silurian outcrop, which extends on the coast effectively to Siccar Point and over a wide area inland to south-west. Graptolites have been collected from finer-grained bands on the descent to the beach, and just round the corner on the left near HWM. Sedimentation structures can be seen in places on the upper and lower surfaces of the greywackes, current-bedding is locally developed, and axial-plane cleavage is seen in some of the finer-grained rocks. </div></td></tr>
</table>JenniferFindlay1https://earthwise.bgs.ac.uk/index.php?title=St._Abb%27s_Head_-_an_excursion&diff=7888&oldid=prevDbk: /* 13 St Abbs Harbour: Quartz-Dolerite Dyke. */2015-03-18T09:12:05Z<p><span dir="auto"><span class="autocomment">13 St Abbs Harbour: Quartz-Dolerite Dyke.</span></span></p>
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<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>It is about 2 km from Pettico Wick along the road from the Lighthouse, to the car park at which the itinerary began. The walk affords fine views to east of the terrain traversed on the excursion. The rocks seen at a few places along the way are all within the greywacke outcrop. In general form and in local detail the topography displays the erosive effects of ice moving south-eastwards, most conspicuously in the over-deepening of the Mire Loch.</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>It is about 2 km from Pettico Wick along the road from the Lighthouse, to the car park at which the itinerary began. The walk affords fine views to east of the terrain traversed on the excursion. The rocks seen at a few places along the way are all within the greywacke outcrop. In general form and in local detail the topography displays the erosive effects of ice moving south-eastwards, most conspicuously in the over-deepening of the Mire Loch.</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr>
<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>==== 13 St Abbs Harbour: Quartz-Dolerite Dyke<del style="font-weight: bold; text-decoration: none;">. </del> ====</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>==== 13 St Abbs Harbour: Quartz-Dolerite Dyke ====</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>An instructive exposure of a quartz-dolerite dyke of Late Carboniferous-?Permian age occurs immediately south of the southern wall of St Abbs Harbour, 800 m from the NNR car park. For most of its length the Harbour wall stands on this dyke, which is about 14 m wide. The well-exposed southern margin of the dyke is fine-grained and shows banding, irregularity of detail, and in corporation of xenoliths up to 30 cm across.</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>An instructive exposure of a quartz-dolerite dyke of Late Carboniferous-?Permian age occurs immediately south of the southern wall of St Abbs Harbour, 800 m from the NNR car park. For most of its length the Harbour wall stands on this dyke, which is about 14 m wide. The well-exposed southern margin of the dyke is fine-grained and shows banding, irregularity of detail, and in corporation of xenoliths up to 30 cm across.</div></td></tr>
<tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;"></ins></div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>===References===</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>===References===</div></td></tr>
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</table>Dbkhttps://earthwise.bgs.ac.uk/index.php?title=St._Abb%27s_Head_-_an_excursion&diff=7887&oldid=prevDbk: /* 4. Hardencarrs Heugh and Burnmouth Harbour: Lavas and Agglomerates */2015-03-18T09:11:53Z<p><span dir="auto"><span class="autocomment">4. Hardencarrs Heugh and Burnmouth Harbour: Lavas and Agglomerates</span></span></p>
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<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>The northward continuation of the cliff path crosses a large body of fine-grained lava, which makes up most of Hardencarrs Heugh. It is well exposed on the northern (inland) face of White Heugh, where steep platy jointing is conspicuously developed. Between Hardencarrs Heugh and Burnmouth Harbour are many small exposures of red lava full of tiny amygdales, locally clearly forming a homogeneous agglomerate, but the distinction between that and unbroken lava is difficult to determine and may not be very significant. Some of the clean wave-washed rock at Burnmouth Harbour is very obviously agglomeratic. </div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>The northward continuation of the cliff path crosses a large body of fine-grained lava, which makes up most of Hardencarrs Heugh. It is well exposed on the northern (inland) face of White Heugh, where steep platy jointing is conspicuously developed. Between Hardencarrs Heugh and Burnmouth Harbour are many small exposures of red lava full of tiny amygdales, locally clearly forming a homogeneous agglomerate, but the distinction between that and unbroken lava is difficult to determine and may not be very significant. Some of the clean wave-washed rock at Burnmouth Harbour is very obviously agglomeratic. </div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr>
<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>==== 5. Horsecastle Bay: Agglomerate, Brecciated Lavas, Lamprophyre Dyke ====[[File:P005893.jpg|thumb|200px|right|St. Abb's Head, Horsecastle Bay. View N. Grits and lava. Bedded tuffaceous grits overlie massive lava in the foreground, and are overlain on the headland by a later flow with a clearly irregular base. Such interrelations of bedded grits are not uncommon in the predominantly lava sequence of St. Abb's Head. Lower Old Red Sandstone. [https://194.66.252.158/asset-bank/action/viewAsset?id=5142 P005893]]]</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>==== 5. Horsecastle Bay: Agglomerate, Brecciated Lavas, Lamprophyre Dyke ====</div></td></tr>
<tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>[[File:P005893.jpg|thumb|200px|right|St. Abb's Head, Horsecastle Bay. View N. Grits and lava. Bedded tuffaceous grits overlie massive lava in the foreground, and are overlain on the headland by a later flow with a clearly irregular base. Such interrelations of bedded grits are not uncommon in the predominantly lava sequence of St. Abb's Head. Lower Old Red Sandstone. [https://194.66.252.158/asset-bank/action/viewAsset?id=5142 P005893]]]</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>From Burnmouth Harbour follow H.W.M. for 200 m to a little embayment on the north side of the headland of Horse Castle, where the agglomeratic country rock is cut by 3-m dyke of highly micaceous lamprophyre. It follows a curved north-easterly course, is cut by faults, and has two thin offshoots on its south-eastern side. It could be the same intrusion as that noted earlier at White Heugh and on Bell Hill, and is the only minor intrusion so far recognised in the lava sequence. Most of the rock between Burnmouth Harbour and Horsecastle Bay is roughly bedded brecciated lava. Thin layers of unbroken lava are present, being clearly distinguishable on the stack of Horsecastle Rocks, and one at least 4.5m thick caps the cliffs at Horse Castle, near the lamprophyre dyke. Typical broken lava is well exposed on the south- eastern side of Horsecastle Bay, where many large tabulate or rounded fragments of lava lie parallel to the major bedding fractures. The rock is thought to result from the spasmodic solidification of lava during the continuing movement of the flow as a whole.</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>From Burnmouth Harbour follow H.W.M. for 200 m to a little embayment on the north side of the headland of Horse Castle, where the agglomeratic country rock is cut by 3-m dyke of highly micaceous lamprophyre. It follows a curved north-easterly course, is cut by faults, and has two thin offshoots on its south-eastern side. It could be the same intrusion as that noted earlier at White Heugh and on Bell Hill, and is the only minor intrusion so far recognised in the lava sequence. Most of the rock between Burnmouth Harbour and Horsecastle Bay is roughly bedded brecciated lava. Thin layers of unbroken lava are present, being clearly distinguishable on the stack of Horsecastle Rocks, and one at least 4.5m thick caps the cliffs at Horse Castle, near the lamprophyre dyke. Typical broken lava is well exposed on the south- eastern side of Horsecastle Bay, where many large tabulate or rounded fragments of lava lie parallel to the major bedding fractures. The rock is thought to result from the spasmodic solidification of lava during the continuing movement of the flow as a whole.</div></td></tr>
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</table>Dbkhttps://earthwise.bgs.ac.uk/index.php?title=St._Abb%27s_Head_-_an_excursion&diff=7882&oldid=prevScotfot at 19:15, 16 March 20152015-03-16T19:15:58Z<p></p>
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<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>==== Introduction ====</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>==== Introduction ====</div></td></tr>
<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>The principal object of this excursion is to study the volcanic rocks of Lower Old Red Sandstone (Lower Devonian) age which form the peninsula of St Abb's Head, on the Berwickshire coast north of St Abb’s and Coldinghame. The excursion could occupy a full day, but as it does not cover a very extensive area it can conveniently be cut short as required. The complete circuit covers a distance of about 8 km, of which about 4 km is over hilly open pasture, 1 km over rough rocky seashore, and nearly 3 km on a surfaced hill-road. The steep grassy slopes above the precipitous cliffs of St Abb's Head demand boots <del style="font-weight: bold; text-decoration: none;">with well-nailed soles or deep-cut rubber soles of the Commando type</del>. The excursion is affected by the state of the tide at only one or two localities, possibly requiring adjustments to the route </div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>The principal object of this excursion is to study the volcanic rocks of Lower Old Red Sandstone (Lower Devonian) age which form the peninsula of St Abb's Head, on the Berwickshire coast north of St Abb’s and Coldinghame. The excursion could occupy a full day, but as it does not cover a very extensive area it can conveniently be cut short as required. The complete circuit covers a distance of about 8 km, of which about 4 km is over hilly open pasture, 1 km over rough rocky seashore, and nearly 3 km on a surfaced hill-road. The steep grassy slopes above the precipitous cliffs of St Abb's Head demand <ins style="font-weight: bold; text-decoration: none;">sturdy </ins>boots. The excursion is affected by the state of the tide at only one or two localities, possibly requiring adjustments to the route </div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>St Abbs lies 7 km south-east of Fast Castle and is reached by the B6438 road from Coldingham. The headland, just north of the village, is a National Nature Reserve, managed jointly by the National Trust for Scotland and the Scottish Wildlife Trust [https://www.nts.org.uk/Property/St-Abbs-Head-National-Nature-Reserve/Property-description NTS-SWT]. Car and coach parking are located beside the information centre and coffee shop at Northfield Farm (NT 913 674), limited car parking is also possible near the Lighthouse (NT 913 692). The excursion is described as starting and finishing at the information centre, where an illustrated guide to the Reserve and other literature are available. </div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>St Abbs lies 7 km south-east of Fast Castle and is reached by the B6438 road from Coldingham. The headland, just north of the village, is a National Nature Reserve, managed jointly by the National Trust for Scotland and the Scottish Wildlife Trust [https://www.nts.org.uk/Property/St-Abbs-Head-National-Nature-Reserve/Property-description NTS-SWT]. Car and coach parking are located beside the information centre and coffee shop at Northfield Farm (NT 913 674), limited car parking is also possible near the Lighthouse (NT 913 692). The excursion is described as starting and finishing at the information centre, where an illustrated guide to the Reserve and other literature are available. </div></td></tr>
</table>Scotfothttps://earthwise.bgs.ac.uk/index.php?title=St._Abb%27s_Head_-_an_excursion&diff=7421&oldid=prevScotfot at 20:25, 7 March 20152015-03-07T20:25:15Z<p></p>
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<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr>
<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>'''By D.C.Greig. From Scottish Borders geology: an excursion guide edited by A.D. McAdam, E.N.K. Clarkson, P. Stone. Edinburgh : Scottish Academic Press, 1972.'''</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>'''By D.C.Greig. From Scottish Borders geology: an excursion guide edited by A.D. McAdam, E.N.K. Clarkson, P. Stone. Edinburgh : Scottish Academic Press <ins style="font-weight: bold; text-decoration: none;">(for [https://www.edinburghgeolsoc.org/ Edinburgh Geological Society])</ins>, 1972.'''</div></td></tr>
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<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>O.S. 1:50 000 Sheet 67 Duns and Dunbar</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>O.S. 1:50 000 Sheet 67 Duns and Dunbar</div></td></tr>
</table>Scotfothttps://earthwise.bgs.ac.uk/index.php?title=St._Abb%27s_Head_-_an_excursion&diff=7405&oldid=prevScotfot: /* 5. Horsecastle Bay: Agglomerate, Brecciated Lavas, Lamprophyre Dyke */2015-03-07T19:44:03Z<p><span dir="auto"><span class="autocomment">5. Horsecastle Bay: Agglomerate, Brecciated Lavas, Lamprophyre Dyke</span></span></p>
<table style="background-color: #fff; color: #202122;" data-mw="interface">
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<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>The northward continuation of the cliff path crosses a large body of fine-grained lava, which makes up most of Hardencarrs Heugh. It is well exposed on the northern (inland) face of White Heugh, where steep platy jointing is conspicuously developed. Between Hardencarrs Heugh and Burnmouth Harbour are many small exposures of red lava full of tiny amygdales, locally clearly forming a homogeneous agglomerate, but the distinction between that and unbroken lava is difficult to determine and may not be very significant. Some of the clean wave-washed rock at Burnmouth Harbour is very obviously agglomeratic. </div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>The northward continuation of the cliff path crosses a large body of fine-grained lava, which makes up most of Hardencarrs Heugh. It is well exposed on the northern (inland) face of White Heugh, where steep platy jointing is conspicuously developed. Between Hardencarrs Heugh and Burnmouth Harbour are many small exposures of red lava full of tiny amygdales, locally clearly forming a homogeneous agglomerate, but the distinction between that and unbroken lava is difficult to determine and may not be very significant. Some of the clean wave-washed rock at Burnmouth Harbour is very obviously agglomeratic. </div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr>
<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>==== 5. Horsecastle Bay: Agglomerate, Brecciated Lavas, Lamprophyre Dyke ====</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>==== 5. Horsecastle Bay: Agglomerate, Brecciated Lavas, Lamprophyre Dyke ====<ins style="font-weight: bold; text-decoration: none;">[[File:P005893.jpg|thumb|200px|right|St. Abb's Head, Horsecastle Bay. View N. Grits and lava. Bedded tuffaceous grits overlie massive lava in the foreground, and are overlain on the headland by a later flow with a clearly irregular base. Such interrelations of bedded grits are not uncommon in the predominantly lava sequence of St. Abb's Head. Lower Old Red Sandstone. [https://194.66.252.158/asset-bank/action/viewAsset?id=5142 P005893]]]</ins></div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>From Burnmouth Harbour follow H.W.M. for 200 m to a little embayment on the north side of the headland of Horse Castle, where the agglomeratic country rock is cut by 3-m dyke of highly micaceous lamprophyre. It follows a curved north-easterly course, is cut by faults, and has two thin offshoots on its south-eastern side. It could be the same intrusion as that noted earlier at White Heugh and on Bell Hill, and is the only minor intrusion so far recognised in the lava sequence. Most of the rock between Burnmouth Harbour and Horsecastle Bay is roughly bedded brecciated lava. Thin layers of unbroken lava are present, being clearly distinguishable on the stack of Horsecastle Rocks, and one at least 4.5m thick caps the cliffs at Horse Castle, near the lamprophyre dyke. Typical broken lava is well exposed on the south- eastern side of Horsecastle Bay, where many large tabulate or rounded fragments of lava lie parallel to the major bedding fractures. The rock is thought to result from the spasmodic solidification of lava during the continuing movement of the flow as a whole.</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>From Burnmouth Harbour follow H.W.M. for 200 m to a little embayment on the north side of the headland of Horse Castle, where the agglomeratic country rock is cut by 3-m dyke of highly micaceous lamprophyre. It follows a curved north-easterly course, is cut by faults, and has two thin offshoots on its south-eastern side. It could be the same intrusion as that noted earlier at White Heugh and on Bell Hill, and is the only minor intrusion so far recognised in the lava sequence. Most of the rock between Burnmouth Harbour and Horsecastle Bay is roughly bedded brecciated lava. Thin layers of unbroken lava are present, being clearly distinguishable on the stack of Horsecastle Rocks, and one at least 4.5m thick caps the cliffs at Horse Castle, near the lamprophyre dyke. Typical broken lava is well exposed on the south- eastern side of Horsecastle Bay, where many large tabulate or rounded fragments of lava lie parallel to the major bedding fractures. The rock is thought to result from the spasmodic solidification of lava during the continuing movement of the flow as a whole.</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr>
</table>Scotfothttps://earthwise.bgs.ac.uk/index.php?title=St._Abb%27s_Head_-_an_excursion&diff=7403&oldid=prevScotfot: /* Introduction */2015-03-07T19:37:49Z<p><span dir="auto"><span class="autocomment">Introduction</span></span></p>
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<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>The lavas of St Abb's Head are generally andesitic, but the constituent minerals are so altered that classification is often in doubt. In thin section the feldspars appear, when fresh, to be mainly oligoclase or andesine, and the ferromagnesians, usually altered to iron-ore, may show the crystal form of hornblende or augite. More basic rock, with labradorite and olivine, is quite common. Micas, particularly biotite, are often present and in somerocks are abundant. The rocks are generally microporphyritic, and under the microscope many show well developed flow-structure. The upper and lower parts of the flows are often highly amygdaloidal, the vesicles being filled with silica and/or calcite. In general type the lavas are similar to the mica-andesites of the Cheviot Hills (Geikie 1864<ref>Geikie, A. 1864. The Geology of Eastern Berwickshire. Mem. Geol. Surv. Scot.</ref>, 1897<ref>Geikie, J.1897. Geology and Petrology of St Abb's Head. Proc. R. Soc. Edinb.14, 177-193.</ref>, Greig 1988<ref>Greig, D.C. 1988. Geology of the Eyemouth district. Mem. Brit. Geol. Surv. Hutton, J. 1795. Theory of the Earth. William Creech, Edinburgh.</ref>).</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>The lavas of St Abb's Head are generally andesitic, but the constituent minerals are so altered that classification is often in doubt. In thin section the feldspars appear, when fresh, to be mainly oligoclase or andesine, and the ferromagnesians, usually altered to iron-ore, may show the crystal form of hornblende or augite. More basic rock, with labradorite and olivine, is quite common. Micas, particularly biotite, are often present and in somerocks are abundant. The rocks are generally microporphyritic, and under the microscope many show well developed flow-structure. The upper and lower parts of the flows are often highly amygdaloidal, the vesicles being filled with silica and/or calcite. In general type the lavas are similar to the mica-andesites of the Cheviot Hills (Geikie 1864<ref>Geikie, A. 1864. The Geology of Eastern Berwickshire. Mem. Geol. Surv. Scot.</ref>, 1897<ref>Geikie, J.1897. Geology and Petrology of St Abb's Head. Proc. R. Soc. Edinb.14, 177-193.</ref>, Greig 1988<ref>Greig, D.C. 1988. Geology of the Eyemouth district. Mem. Brit. Geol. Surv. Hutton, J. 1795. Theory of the Earth. William Creech, Edinburgh.</ref>).</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr>
<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>[[File:StAbbsHeadExcursionMap.jpg|thumb|600px|<del style="font-weight: bold; text-decoration: none;">center</del>|St Abb's Head</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>[[File:StAbbsHeadExcursionMap.jpg|thumb|600px|<ins style="font-weight: bold; text-decoration: none;">right</ins>|St Abb's Head<ins style="font-weight: bold; text-decoration: none;">]]</ins></div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>==== 1. Northfield: Viewpoint ====</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>==== 1. Northfield: Viewpoint ====</div></td></tr>
</table>Scotfothttps://earthwise.bgs.ac.uk/index.php?title=St._Abb%27s_Head_-_an_excursion&diff=7402&oldid=prevScotfot at 19:36, 7 March 20152015-03-07T19:36:56Z<p></p>
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<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>St Abbs lies 7 km south-east of Fast Castle and is reached by the B6438 road from Coldingham. The headland, just north of the village, is a National Nature Reserve, managed jointly by the National Trust for Scotland and the Scottish Wildlife Trust [https://www.nts.org.uk/Property/St-Abbs-Head-National-Nature-Reserve/Property-description NTS-SWT]. Car and coach parking are located beside the information centre and coffee shop at Northfield Farm (NT 913 674), limited car parking is also possible near the Lighthouse (NT 913 692). The excursion is described as starting and finishing at the information centre, where an illustrated guide to the Reserve and other literature are available. </div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>St Abbs lies 7 km south-east of Fast Castle and is reached by the B6438 road from Coldingham. The headland, just north of the village, is a National Nature Reserve, managed jointly by the National Trust for Scotland and the Scottish Wildlife Trust [https://www.nts.org.uk/Property/St-Abbs-Head-National-Nature-Reserve/Property-description NTS-SWT]. Car and coach parking are located beside the information centre and coffee shop at Northfield Farm (NT 913 674), limited car parking is also possible near the Lighthouse (NT 913 692). The excursion is described as starting and finishing at the information centre, where an illustrated guide to the Reserve and other literature are available. </div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr>
<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>The lavas of St Abb's Head are generally andesitic, but the constituent minerals are so altered that classification is often in doubt. In thin section the feldspars appear, when fresh, to be mainly oligoclase or andesine, and the ferromagnesians, usually altered to iron-ore, may show the crystal form of hornblende or augite. More basic rock, with labradorite and olivine, is quite common. Micas, particularly biotite, are often present and in somerocks are abundant. The rocks are generally microporphyritic, and under the microscope many show well developed flow-structure. The upper and lower parts of the flows are often highly amygdaloidal, the vesicles being filled with silica and/or calcite. In general type the lavas are similar to the mica-andesites of the Cheviot Hills (Geikie 1864<ref>Geikie, A. 1864. The Geology of Eastern Berwickshire. Mem. Geol. Surv. Scot.</ref>, 1897<ref>Geikie, J.1897. Geology and Petrology of St Abb's Head. Proc. R. Soc. Edinb.14, 177-193.</ref>, Greig 1988<ref>Greig, D.C. 1988. Geology of the Eyemouth district. Mem. Brit. Geol. Surv. Hutton, J. 1795. Theory of the Earth. William Creech, Edinburgh.</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>The lavas of St Abb's Head are generally andesitic, but the constituent minerals are so altered that classification is often in doubt. In thin section the feldspars appear, when fresh, to be mainly oligoclase or andesine, and the ferromagnesians, usually altered to iron-ore, may show the crystal form of hornblende or augite. More basic rock, with labradorite and olivine, is quite common. Micas, particularly biotite, are often present and in somerocks are abundant. The rocks are generally microporphyritic, and under the microscope many show well developed flow-structure. The upper and lower parts of the flows are often highly amygdaloidal, the vesicles being filled with silica and/or calcite. In general type the lavas are similar to the mica-andesites of the Cheviot Hills (Geikie 1864<ref>Geikie, A. 1864. The Geology of Eastern Berwickshire. Mem. Geol. Surv. Scot.</ref>, 1897<ref>Geikie, J.1897. Geology and Petrology of St Abb's Head. Proc. R. Soc. Edinb.14, 177-193.</ref>, Greig 1988<ref>Greig, D.C. 1988. Geology of the Eyemouth district. Mem. Brit. Geol. Surv. Hutton, J. 1795. Theory of the Earth. William Creech, Edinburgh<ins style="font-weight: bold; text-decoration: none;">.</ref>)</ins>.</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr>
<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div><del style="font-weight: bold; text-decoration: none;"></ref>)</del>.</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">[[File:StAbbsHeadExcursionMap</ins>.<ins style="font-weight: bold; text-decoration: none;">jpg|thumb|600px|center|St Abb's Head</ins></div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>==== 1. Northfield: Viewpoint ====</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>==== 1. Northfield: Viewpoint ====</div></td></tr>
</table>Scotfothttps://earthwise.bgs.ac.uk/index.php?title=St._Abb%27s_Head_-_an_excursion&diff=7400&oldid=prevScotfot: /* Introduction */2015-03-07T19:33:23Z<p><span dir="auto"><span class="autocomment">Introduction</span></span></p>
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<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td>
<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 19:33, 7 March 2015</td>
</tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l13">Line 13:</td>
<td colspan="2" class="diff-lineno">Line 13:</td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>St Abbs lies 7 km south-east of Fast Castle and is reached by the B6438 road from Coldingham. The headland, just north of the village, is a National Nature Reserve, managed jointly by the National Trust for Scotland and the Scottish Wildlife Trust [https://www.nts.org.uk/Property/St-Abbs-Head-National-Nature-Reserve/Property-description NTS-SWT]. Car and coach parking are located beside the information centre and coffee shop at Northfield Farm (NT 913 674), limited car parking is also possible near the Lighthouse (NT 913 692). The excursion is described as starting and finishing at the information centre, where an illustrated guide to the Reserve and other literature are available. </div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>St Abbs lies 7 km south-east of Fast Castle and is reached by the B6438 road from Coldingham. The headland, just north of the village, is a National Nature Reserve, managed jointly by the National Trust for Scotland and the Scottish Wildlife Trust [https://www.nts.org.uk/Property/St-Abbs-Head-National-Nature-Reserve/Property-description NTS-SWT]. Car and coach parking are located beside the information centre and coffee shop at Northfield Farm (NT 913 674), limited car parking is also possible near the Lighthouse (NT 913 692). The excursion is described as starting and finishing at the information centre, where an illustrated guide to the Reserve and other literature are available. </div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr>
<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>The lavas of St Abb's Head are generally andesitic, but the constituent minerals are so altered that classification is often in doubt. In thin section the feldspars appear, when fresh, to be mainly oligoclase or andesine, and the ferromagnesians, usually altered to iron-ore, may show the crystal form of hornblende or augite. More basic rock, with labradorite and olivine, is quite common. Micas, particularly biotite, are often present and in somerocks are abundant. The rocks are generally microporphyritic, and under the microscope many show well developed flow-structure. The upper and lower parts of the flows are often highly amygdaloidal, the vesicles being filled with silica and/or calcite. In general type the lavas are similar to the mica-andesites of the Cheviot Hills (Geikie 1864, <del style="font-weight: bold; text-decoration: none;">1867</del>, Greig 1988).</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>The lavas of St Abb's Head are generally andesitic, but the constituent minerals are so altered that classification is often in doubt. In thin section the feldspars appear, when fresh, to be mainly oligoclase or andesine, and the ferromagnesians, usually altered to iron-ore, may show the crystal form of hornblende or augite. More basic rock, with labradorite and olivine, is quite common. Micas, particularly biotite, are often present and in somerocks are abundant. The rocks are generally microporphyritic, and under the microscope many show well developed flow-structure. The upper and lower parts of the flows are often highly amygdaloidal, the vesicles being filled with silica and/or calcite. In general type the lavas are similar to the mica-andesites of the Cheviot Hills (Geikie 1864<ins style="font-weight: bold; text-decoration: none;"><ref>Geikie</ins>, <ins style="font-weight: bold; text-decoration: none;">A. 1864. The Geology of Eastern Berwickshire. Mem. Geol. Surv. Scot.</ref></ins>, <ins style="font-weight: bold; text-decoration: none;">1897<ref>Geikie, J.1897. Geology and Petrology of St Abb's Head. Proc. R. Soc. Edinb.14, 177-193.</ref>, Greig 1988<ref></ins>Greig<ins style="font-weight: bold; text-decoration: none;">, D.C. </ins>1988<ins style="font-weight: bold; text-decoration: none;">. Geology of the Eyemouth district. Mem. Brit. Geol. Surv. Hutton, J. 1795. Theory of the Earth. William Creech, Edinburgh.</ins></div></td></tr>
<tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div> </div></td></tr>
<tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;"></ref></ins>).</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>==== 1. Northfield: Viewpoint ====</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>==== 1. Northfield: Viewpoint ====</div></td></tr>
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