Kinloch and surroundings. South side of Loch Scresort, Rum - an excursion

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Map of Excursion 1B, east of Kinloch.
Stratigraphy of the Torridon Group on Rum (after Nicholson, 1992).

Excursion 1B from: Emeleus, C. H. and Troll, V. R. A geological excursion guide to Rum: the Paleocene igneous rocks of the Isle of Rum, Inner Hebrides. Edinburgh : Edinburgh Geological Society in association with NMS Enterprises Limited, 2008.

Introduction Excursion 1A & 1B

The approximate areas covered by each excursion are indicated on Figure 9. Remember that Rum is a National Nature Reserve and prior permission must be obtained from SNH if you need to collect rock samples. Consult the Reserve Manager if in any doubt. As far as possible samples should come from loose material (of which there is usually an abundance).

The boat from Mallaig normally reaches Rum before 2pm, except on summer Saturdays when the early service arrives at about 9am. The first afternoon may be spent around Kinloch, on the sandstones of the Torridon Group and the numerous Paleocene minor intrusions. The latter include basaltic sheets and dykes, and several plugs of feldspathic peridotite and gabbro (See image), (See image). Alternatively, if time on Rum is limited, some or all of the localities in Coire Dubh could be visited (Excursion 2; Figure 13; Localities 2.1 to 2.8).

B. South side of Loch Scresort

From Kinloch Castle go to the White House (the SNH Reserve Office) and take the shore road. Cross a small stream and go down to a rocky promontory immediately to the north-east (See image).

Locality 1.4 White House, Kinloch – picrite dyke cutting sandstone [NM 4044 9928]

Sandstone on the promontory is cut by a broad, north-east-trending picritic dolerite dyke with abundant fresh olivine crystals. This dyke is probably the continuation of the picritic dolerite that cuts Stage 1 rocks in Allt Slugan a’Choilich in Coire Dubh (Excursion 2; Locality 2.2). Continue east past the new ferry terminal (c. 1 km east of the White House) and take the path along the south side of the loch. West-north-west-dipping sandstone belonging to the Scresort Sandstone Member is cut by several thin north-east- to north-north-east-trending basalt dykes and less common south-dipping basalt sheets. Some 400 m east of the ferry terminal, coarse-grained sandstones of the Scresort Sandstone Member (TCAS) give way to progressively finer grained beds down the sequence that make up the Allt Mòr na h-Uamha Member (TCAM) (See image).

Locality 1.5 Cro nan Laogh – Torridonian sandstone displaced along the low-angle Mullach Ard Fault [NM 4208 9893]

At Cro nan Laogh, cyclically interbedded siltstones and sandstones in the Allt Mòr na h-Uamha Member are well exposed and a thin (50 cm) basalt sheet is intruded near the base of the cliff. Immediately to the east, coarse-grained sandstones belonging to the Scresort Sandstone Member are downfaulted against the finer grained beds by the Mullach Ard Fault. This fault extends south to Bàgh na h-Uamha [NM 423 974] and is inclined at c. 35º in an easterly direction. It is one of several low-angle faults in eastern and southern Rum on which substantial masses of country rocks are thought to have slid off the central complex when a dome-like structure developed early in Stage 1. Return to Kinloch. (Total distance c. 4 km.)

References

At all times follow: The Scottish Access Codeand Code of Conduct for Fieldwork .