OR/15/048 Regional geology and hydrogeology - Revision history

Dbk: /* Current issues in groundwater quality */

2015-09-11T15:02:46Z

Current issues in groundwater quality

← Older revision		Revision as of 16:02, 11 September 2015
Line 238:		Line 238:
	<nowiki>*</nowiki>Assuming all NH<sub>4</sub>-N is oxidised to NO<sub>3</sub> on infiltration.		<nowiki>*</nowiki>Assuming all NH<sub>4</sub>-N is oxidised to NO<sub>3</sub> on infiltration.
	</center>		</center>
	[[Image:OR15048 fig7.jpg\|thumb\|~~cneter~~\|400px\|'''Figure 7''' Source Protection Zones in the study area.]]		[[Image:OR15048 fig7.jpg\|thumb\|center\|400px\|'''Figure 7''' Source Protection Zones in the study area.]]

	Source protection zones (SPZs) around boreholes have been identified by the EA (Figure 7). These show the risk of contamination from activities which may cause pollution. They are zoned according to the risk in terms of time for the pollution to travel to the borehole and extent of the contamination risk. Within the Corallian large SPZs are located around Pickering, Scarborough and East Ness. Local SPZs (~500m in diameter) are sparsely distributed around the periphery of valley bottom, within the Hambleton and Howardian Hills, and in the area south of Malton (EA, 2015<ref name="EA 2015"> EA. 2015. What's in your backyard? Interactive maps http://www.environment- agency.gov.uk/homeandleisure/37793.aspx Accessed 10/7/15. [cited 10/7/15]. </ref>).		Source protection zones (SPZs) around boreholes have been identified by the EA (Figure 7). These show the risk of contamination from activities which may cause pollution. They are zoned according to the risk in terms of time for the pollution to travel to the borehole and extent of the contamination risk. Within the Corallian large SPZs are located around Pickering, Scarborough and East Ness. Local SPZs (~500m in diameter) are sparsely distributed around the periphery of valley bottom, within the Hambleton and Howardian Hills, and in the area south of Malton (EA, 2015<ref name="EA 2015"> EA. 2015. What's in your backyard? Interactive maps http://www.environment- agency.gov.uk/homeandleisure/37793.aspx Accessed 10/7/15. [cited 10/7/15]. </ref>).

Dbk at 15:02, 11 September 2015

2015-09-11T15:02:23Z

← Older revision		Revision as of 16:02, 11 September 2015
Line 70:		Line 70:
	The beginning of the Lower Calcareous Grit Formation is mostly defined by the gradual replacement of the argillaceous conditions of the Oxford Clay deposition with an influx of fine arenaceous material. The lower Calcareous Grit Formation is the same age as the Oxford Clay. The only exception to this is in the south-west part of the Hambleton Hills, where the Lower Calcaerous Grit Formation lies on Middle Jurassic beds, as the Oxford Clay is missing (Cope, 2006<ref name="Cope 2006"></ref>; Wilson, 1948<ref name="Wilson 1948"></ref>; Wilson, 1949<ref name="Wilson 1949"> WILSON, V. 1949. The Lower Corallian Rocks of the Yorkshire Coast and Hackness Hills. ''Proceedings of the Geologists' Association'', Vol. 60, 235–271. </ref>). The formation generally comprises fine- to medium-grained calcareous sandstones which attains maximum thickness in the Tabular and Hambleton Hills, thinning southwards and eastwards towards the coast (Allen et al., 1997<ref name="Allen 1997"></ref>; Wilson, 1948<ref name="Wilson 1948"></ref>). Coastal sections have shown exposed Lower Calcareous Grit Formation divided into three units. The upper unit is known as the 'Ball Beds' and is 3–5 m thick. The 'Ball Beds' comprise very ferruginous sandstone containing large, gritty, fossiliferous calcareous concretions. A hard grey siliceous sandstone 1–2 m thick underlies the 'Ball Beds'. The lower unit is 12–14 m thick and comprises thickly bedded sandstone with siliceous cement. The cement is frequently concentrated into small masses which weather out in irregular nodular bands (Wilson, 1948<ref name="Wilson 1948"></ref>).		The beginning of the Lower Calcareous Grit Formation is mostly defined by the gradual replacement of the argillaceous conditions of the Oxford Clay deposition with an influx of fine arenaceous material. The lower Calcareous Grit Formation is the same age as the Oxford Clay. The only exception to this is in the south-west part of the Hambleton Hills, where the Lower Calcaerous Grit Formation lies on Middle Jurassic beds, as the Oxford Clay is missing (Cope, 2006<ref name="Cope 2006"></ref>; Wilson, 1948<ref name="Wilson 1948"></ref>; Wilson, 1949<ref name="Wilson 1949"> WILSON, V. 1949. The Lower Corallian Rocks of the Yorkshire Coast and Hackness Hills. ''Proceedings of the Geologists' Association'', Vol. 60, 235–271. </ref>). The formation generally comprises fine- to medium-grained calcareous sandstones which attains maximum thickness in the Tabular and Hambleton Hills, thinning southwards and eastwards towards the coast (Allen et al., 1997<ref name="Allen 1997"></ref>; Wilson, 1948<ref name="Wilson 1948"></ref>). Coastal sections have shown exposed Lower Calcareous Grit Formation divided into three units. The upper unit is known as the 'Ball Beds' and is 3–5 m thick. The 'Ball Beds' comprise very ferruginous sandstone containing large, gritty, fossiliferous calcareous concretions. A hard grey siliceous sandstone 1–2 m thick underlies the 'Ball Beds'. The lower unit is 12–14 m thick and comprises thickly bedded sandstone with siliceous cement. The cement is frequently concentrated into small masses which weather out in irregular nodular bands (Wilson, 1948<ref name="Wilson 1948"></ref>).

	[[Image:~~OR/15048~~ fig6.jpg\|thumb\|center\|400px\| '''Figure 6''' Geology in and around the Vale of Pickering.]]		[[Image:OR15048 fig6.jpg\|thumb\|center\|400px\| '''Figure 6''' Geology in and around the Vale of Pickering.]]

	In the escarpments north of Kirkbymoorside and Helmsley the Grit becomes siliceous, because of the presence of siliceous spicules, and frequent chert bands. The grit varies from a hard siliceous spicule-bearing rock in the west to gritty limestone beds with soft sandstones in the southeast (Wilson, 1948<ref name="Wilson 1948"></ref>).		In the escarpments north of Kirkbymoorside and Helmsley the Grit becomes siliceous, because of the presence of siliceous spicules, and frequent chert bands. The grit varies from a hard siliceous spicule-bearing rock in the west to gritty limestone beds with soft sandstones in the southeast (Wilson, 1948<ref name="Wilson 1948"></ref>).
Line 238:		Line 238:
	<nowiki>*</nowiki>Assuming all NH<sub>4</sub>-N is oxidised to NO<sub>3</sub> on infiltration.		<nowiki>*</nowiki>Assuming all NH<sub>4</sub>-N is oxidised to NO<sub>3</sub> on infiltration.
	</center>		</center>
	[[Image:~~OR/15048~~ fig7.jpg\|thumb\|cneter\|400px\|'''Figure 7''' Source Protection Zones in the study area.]]		[[Image:OR15048 fig7.jpg\|thumb\|cneter\|400px\|'''Figure 7''' Source Protection Zones in the study area.]]

	Source protection zones (SPZs) around boreholes have been identified by the EA (Figure 7). These show the risk of contamination from activities which may cause pollution. They are zoned according to the risk in terms of time for the pollution to travel to the borehole and extent of the contamination risk. Within the Corallian large SPZs are located around Pickering, Scarborough and East Ness. Local SPZs (~500m in diameter) are sparsely distributed around the periphery of valley bottom, within the Hambleton and Howardian Hills, and in the area south of Malton (EA, 2015<ref name="EA 2015"> EA. 2015. What's in your backyard? Interactive maps http://www.environment- agency.gov.uk/homeandleisure/37793.aspx Accessed 10/7/15. [cited 10/7/15]. </ref>).		Source protection zones (SPZs) around boreholes have been identified by the EA (Figure 7). These show the risk of contamination from activities which may cause pollution. They are zoned according to the risk in terms of time for the pollution to travel to the borehole and extent of the contamination risk. Within the Corallian large SPZs are located around Pickering, Scarborough and East Ness. Local SPZs (~500m in diameter) are sparsely distributed around the periphery of valley bottom, within the Hambleton and Howardian Hills, and in the area south of Malton (EA, 2015<ref name="EA 2015"> EA. 2015. What's in your backyard? Interactive maps http://www.environment- agency.gov.uk/homeandleisure/37793.aspx Accessed 10/7/15. [cited 10/7/15]. </ref>).

Dbk at 12:53, 11 September 2015

2015-09-11T12:53:15Z

← Older revision		Revision as of 13:53, 11 September 2015
Line 70:		Line 70:
	The beginning of the Lower Calcareous Grit Formation is mostly defined by the gradual replacement of the argillaceous conditions of the Oxford Clay deposition with an influx of fine arenaceous material. The lower Calcareous Grit Formation is the same age as the Oxford Clay. The only exception to this is in the south-west part of the Hambleton Hills, where the Lower Calcaerous Grit Formation lies on Middle Jurassic beds, as the Oxford Clay is missing (Cope, 2006<ref name="Cope 2006"></ref>; Wilson, 1948<ref name="Wilson 1948"></ref>; Wilson, 1949<ref name="Wilson 1949"> WILSON, V. 1949. The Lower Corallian Rocks of the Yorkshire Coast and Hackness Hills. ''Proceedings of the Geologists' Association'', Vol. 60, 235–271. </ref>). The formation generally comprises fine- to medium-grained calcareous sandstones which attains maximum thickness in the Tabular and Hambleton Hills, thinning southwards and eastwards towards the coast (Allen et al., 1997<ref name="Allen 1997"></ref>; Wilson, 1948<ref name="Wilson 1948"></ref>). Coastal sections have shown exposed Lower Calcareous Grit Formation divided into three units. The upper unit is known as the 'Ball Beds' and is 3–5 m thick. The 'Ball Beds' comprise very ferruginous sandstone containing large, gritty, fossiliferous calcareous concretions. A hard grey siliceous sandstone 1–2 m thick underlies the 'Ball Beds'. The lower unit is 12–14 m thick and comprises thickly bedded sandstone with siliceous cement. The cement is frequently concentrated into small masses which weather out in irregular nodular bands (Wilson, 1948<ref name="Wilson 1948"></ref>).		The beginning of the Lower Calcareous Grit Formation is mostly defined by the gradual replacement of the argillaceous conditions of the Oxford Clay deposition with an influx of fine arenaceous material. The lower Calcareous Grit Formation is the same age as the Oxford Clay. The only exception to this is in the south-west part of the Hambleton Hills, where the Lower Calcaerous Grit Formation lies on Middle Jurassic beds, as the Oxford Clay is missing (Cope, 2006<ref name="Cope 2006"></ref>; Wilson, 1948<ref name="Wilson 1948"></ref>; Wilson, 1949<ref name="Wilson 1949"> WILSON, V. 1949. The Lower Corallian Rocks of the Yorkshire Coast and Hackness Hills. ''Proceedings of the Geologists' Association'', Vol. 60, 235–271. </ref>). The formation generally comprises fine- to medium-grained calcareous sandstones which attains maximum thickness in the Tabular and Hambleton Hills, thinning southwards and eastwards towards the coast (Allen et al., 1997<ref name="Allen 1997"></ref>; Wilson, 1948<ref name="Wilson 1948"></ref>). Coastal sections have shown exposed Lower Calcareous Grit Formation divided into three units. The upper unit is known as the 'Ball Beds' and is 3–5 m thick. The 'Ball Beds' comprise very ferruginous sandstone containing large, gritty, fossiliferous calcareous concretions. A hard grey siliceous sandstone 1–2 m thick underlies the 'Ball Beds'. The lower unit is 12–14 m thick and comprises thickly bedded sandstone with siliceous cement. The cement is frequently concentrated into small masses which weather out in irregular nodular bands (Wilson, 1948<ref name="Wilson 1948"></ref>).

	[[Image:OR/~~15/048~~ fig6.jpg\|thumb\|center\|400px\| '''Figure 6''' Geology in and around the Vale of Pickering.]]		[[Image:OR/15048 fig6.jpg\|thumb\|center\|400px\| '''Figure 6''' Geology in and around the Vale of Pickering.]]

	In the escarpments north of Kirkbymoorside and Helmsley the Grit becomes siliceous, because of the presence of siliceous spicules, and frequent chert bands. The grit varies from a hard siliceous spicule-bearing rock in the west to gritty limestone beds with soft sandstones in the southeast (Wilson, 1948<ref name="Wilson 1948"></ref>).		In the escarpments north of Kirkbymoorside and Helmsley the Grit becomes siliceous, because of the presence of siliceous spicules, and frequent chert bands. The grit varies from a hard siliceous spicule-bearing rock in the west to gritty limestone beds with soft sandstones in the southeast (Wilson, 1948<ref name="Wilson 1948"></ref>).
Line 238:		Line 238:
	<nowiki>*</nowiki>Assuming all NH<sub>4</sub>-N is oxidised to NO<sub>3</sub> on infiltration.		<nowiki>*</nowiki>Assuming all NH<sub>4</sub>-N is oxidised to NO<sub>3</sub> on infiltration.
	</center>		</center>
	[[Image:~~OR15048~~ fig7.jpg\|thumb\|cneter\|400px\|'''Figure 7''' Source Protection Zones in the study area.]]		[[Image:OR/15048 fig7.jpg\|thumb\|cneter\|400px\|'''Figure 7''' Source Protection Zones in the study area.]]

	Source protection zones (SPZs) around boreholes have been identified by the EA (Figure 7). These show the risk of contamination from activities which may cause pollution. They are zoned according to the risk in terms of time for the pollution to travel to the borehole and extent of the contamination risk. Within the Corallian large SPZs are located around Pickering, Scarborough and East Ness. Local SPZs (~500m in diameter) are sparsely distributed around the periphery of valley bottom, within the Hambleton and Howardian Hills, and in the area south of Malton (EA, 2015<ref name="EA 2015"> EA. 2015. What's in your backyard? Interactive maps http://www.environment- agency.gov.uk/homeandleisure/37793.aspx Accessed 10/7/15. [cited 10/7/15]. </ref>).		Source protection zones (SPZs) around boreholes have been identified by the EA (Figure 7). These show the risk of contamination from activities which may cause pollution. They are zoned according to the risk in terms of time for the pollution to travel to the borehole and extent of the contamination risk. Within the Corallian large SPZs are located around Pickering, Scarborough and East Ness. Local SPZs (~500m in diameter) are sparsely distributed around the periphery of valley bottom, within the Hambleton and Howardian Hills, and in the area south of Malton (EA, 2015<ref name="EA 2015"> EA. 2015. What's in your backyard? Interactive maps http://www.environment- agency.gov.uk/homeandleisure/37793.aspx Accessed 10/7/15. [cited 10/7/15]. </ref>).

Dbk: /* Current issues in groundwater quality */

2015-09-10T14:32:10Z

Current issues in groundwater quality

← Older revision		Revision as of 15:32, 10 September 2015
Line 189:		Line 189:
	\|-		\|-
	\| SEC		\| SEC
	\| µS ~~cm–1~~		\| µS cm<sup>-1</sup>
	\| 17		\| 17
	\| 51		\| 51
Line 227:		Line 227:
	\|-		\|-
	\| NO<sub>3</sub>–N		\| NO<sub>3</sub>–N
	\| mg ~~L–1~~		\| mg L<sup>–1</sup>
	\| 0.09		\| 0.09
	\| 0.73*		\| 0.73*
	\|-		\|-
	\| NH<sub>4</sub>–N		\| NH<sub>4</sub>–N
	\| mg ~~L–1~~		\| mg L<sup>–1</sup>
	\| 0.15		\| 0.15
	\|		\|

Dbk at 14:09, 10 September 2015

2015-09-10T14:09:56Z

Show changes

Dbk: /* Rainfall chemistry */

2015-09-10T12:56:30Z

Rainfall chemistry

← Older revision		Revision as of 13:56, 10 September 2015
Line 169:		Line 169:
	Table 3.4 shows the chemical composition of rainfall from the Moor House monitoring site [NY 757 328] located in the north Pennines, near to the source of the River Tees, 115 km north-west of Pickering.		Table 3.4 shows the chemical composition of rainfall from the Moor House monitoring site [NY 757 328] located in the north Pennines, near to the source of the River Tees, 115 km north-west of Pickering.

	Concentrations of Na and Cl in the Moor House analyses suggest that there are maritime influences. This site is >60 km from the coast. Concentrations are therefore likely to be higher in the Vale of Pickering rainfall than the Moor House rainfall. The Vale of Pickering is proximal to the coast, and likely to be influenced by airborne marine salts (Shand et al., 2007<ref name="Shand 2007"> SHAND, P, EDMUNDS, W M, LAWRENCE, A R, SMEDLEY, P L, and BURKE, S. 2007. The natural (baseline) quality of groundwater in England and Wales. British Geological Survey & Environment Agency, RR/07/06 & NC/99/74/24 (Keyworth and Solihull). </ref>). Rainwater is naturally acidic owing to the dissolution of atmospheric ~~CO2~~, which forms a weak solution of carbonic acid with an equilibrium pH of around 5.7. The Moor House rain water is pH 5.6 indicating there are few airborne pollutants present, such as oxides of sulphur (SOx) and nitrogen (NOx) which are capable of further acidification (Shand et al., 2007<ref name="Shand 2007"></ref>). Sites within the study area that are closer to industrial atmospheric inputs are likely to contain higher concentrations of SOx and NOx and have a lower pH. If it is assumed that all the NH<sub>4</sub> in rainfall oxidises to NO<sub>3</sub> on infiltration to groundwater, baseline concentrations of dissolved NO<sub>3</sub>-N derived from rainfall alone are likely to be in the order of 0.73 mg L<sup>-1</sup> or less. The pH of recharge may be even lower than that measured in the rainfall owing to the oxidation of NH<sub>4</sub><sup>+</sup> ions to NO<sub>3</sub> which results in the release of H+ ions and concentration by evapotranspiration. This process is reflected in the pH of recharge, which is typically pH 3–5 (Shand et al., 2007<ref name="Shand 2007"></ref>; Smedley and Allen, 2004<ref name="Smedley 2004">SMEDLEY, P L, and ALLEN, D. 2004. The Granites of south-west England. British Geological Survey and Environment Agency, BGS Report CR/04/255; Environment Agency Report NC/99/74/16 (Keyworth and Solihull).</ref>). Mineral dissolution reactions within the calcareous beds will be responsible for buffering these pH values, indeed the pH of waters in calcareous soils and aquifers rarely occurs below 6.5 (Abesser et al., 2005<ref name="Abesser 2005">ABESSER, C, SHAND, P, and INGRAM, J. 2005. The Millstone Grit of Northern England. British Geological Survey and Environment Agency, BGS Report CR/05/015N; Environment Agency Report NC/99/74/22 (Keyworth and Solihull).</ref> ; Kinniburgh and Edmunds, 1986<ref name="Kinniburgh 1986"> KINNIBURGH, D G, and EDMUNDS, W M. 1986. The susceptibility of UK groundwaters to acid deposition. Hydrogeological Report, British Geological Survey No. 86/3. </ref>).		Concentrations of Na and Cl in the Moor House analyses suggest that there are maritime influences. This site is >60 km from the coast. Concentrations are therefore likely to be higher in the Vale of Pickering rainfall than the Moor House rainfall. The Vale of Pickering is proximal to the coast, and likely to be influenced by airborne marine salts (Shand et al., 2007<ref name="Shand 2007">SHAND, P, EDMUNDS, W M, LAWRENCE, A R, SMEDLEY, P L, and BURKE, S. 2007. The natural (baseline) quality of groundwater in England and Wales. British Geological Survey & Environment Agency, RR/07/06 & NC/99/74/24 (Keyworth and Solihull). </ref>). Rainwater is naturally acidic owing to the dissolution of atmospheric CO<sub>2</sub>, which forms a weak solution of carbonic acid with an equilibrium pH of around 5.7. The Moor House rain water is pH 5.6 indicating there are few airborne pollutants present, such as oxides of sulphur (SOx) and nitrogen (NOx) which are capable of further acidification (Shand et al., 2007<ref name="Shand 2007"></ref>). Sites within the study area that are closer to industrial atmospheric inputs are likely to contain higher concentrations of SOx and NOx and have a lower pH. If it is assumed that all the NH<sub>4</sub> in rainfall oxidises to NO<sub>3</sub> on infiltration to groundwater, baseline concentrations of dissolved NO<sub>3</sub>-N derived from rainfall alone are likely to be in the order of 0.73 mg L<sup>-1</sup> or less. The pH of recharge may be even lower than that measured in the rainfall owing to the oxidation of NH<sub>4</sub><sup>+</sup> ions to NO<sub>3</sub> which results in the release of H+ ions and concentration by evapotranspiration. This process is reflected in the pH of recharge, which is typically pH 3–5 (Shand et al., 2007<ref name="Shand 2007"></ref>; Smedley and Allen, 2004<ref name="Smedley 2004">SMEDLEY, P L, and ALLEN, D. 2004. The Granites of south-west England. British Geological Survey and Environment Agency, BGS Report CR/04/255; Environment Agency Report NC/99/74/16 (Keyworth and Solihull).</ref>). Mineral dissolution reactions within the calcareous beds will be responsible for buffering these pH values, indeed the pH of waters in calcareous soils and aquifers rarely occurs below 6.5 (Abesser et al., 2005<ref name="Abesser 2005">ABESSER, C, SHAND, P, and INGRAM, J. 2005. The Millstone Grit of Northern England. British Geological Survey and Environment Agency, BGS Report CR/05/015N; Environment Agency Report NC/99/74/22 (Keyworth and Solihull).</ref> ; Kinniburgh and Edmunds, 1986<ref name="Kinniburgh 1986"> KINNIBURGH, D G, and EDMUNDS, W M. 1986. The susceptibility of UK groundwaters to acid deposition. Hydrogeological Report, British Geological Survey No. 86/3. </ref>).

	==Current issues in groundwater quality ==		==Current issues in groundwater quality ==

Dbk: /* Geological setting */

2015-09-10T12:55:34Z

Geological setting

← Older revision		Revision as of 13:55, 10 September 2015
Line 5:		Line 5:
	During the Jurassic Period Britain was situated between 30 and 40º north of the equator. The warm, humid climate represented a change in climatic regime following the arid Permian and Triassic (Cope, 2006<ref name="Cope 2006">COPE, J C W. 2006. Jurassic: The Returning Seas. 559 in The Geology of England and Wales. BRENCHLEY, P J, and RAWSON, P F (editors). (London: The geological Society.)</ref>; McLeish, 1992<ref name="Mcleish 1992">MCLEISH, A. 1992. ''Geological Science''. (Cheltenham: Nelson Thornes Ltd.)</ref>). Throughout much of the Jurassic, Britain was covered by shallow seas; the sea rises being considered related to the creation of oceanic ridges as the supercontinent Pangaea started to break up (McLeish, 1992<ref name="Mcleish 1992"></ref>). Jurassic sedimentary deposition was hence affected by a series of transgressions and regressions (Allen et al., 1997<ref name="Allen 1997">ALLEN, D J, BREWERTON, L M, COLEBY, L M, GIBBS, B R, LEWIS, M A, MACDONALD, A M, WAGSTAFF, S, and WILLIAMS, A T. 1997. The physical properties of major aquifers in England and Wales. ''British Geological Survey'', WD/97/34 (Keyworth).</ref>). The Jurassic Period is subdivided into three series, Lower, Middle and Upper. The Upper Jurassic series is further subdivided into Oxfordian, Kimmeridgian and Tithonian. The Jurassic rocks in the Vale of Pickering are of Oxfordian age and can be conveniently divided into three divisions based on lithological character. These divisions are the Oxford Clay Formation, the Corallian Group, and the West Walton, Ampthill and Kimmeridge Clay formations (Reeves et al., 1978<ref name="Reeves 1978"> REEVES, M J, PARRY, E L, and RICHARDSON, G. 1978. Preliminary investigation of the groundwater resources of the western part of the Vale of Pickering. Quarterly Journal of Engineering Geology, Vol. 11, 253–262. </ref>). The Upper Jurassic rocks are entirely of marine origin. Marine regression had interrupted eustatic sea-level rise, causing the deposition of the Corallian Group (Powell, 2010<ref name="Powell 2010"> POWELL, J H. 2010. Jurassic sedimentation in the Cleveland Basin: a review. Proceedings of the Yorkshire Geological Society, Vol. 58, 21–72. </ref>). The subsequent re-advance of the sea resulted in the deposition of bituminous clay over the Corallian strata (McLeish, 1992<ref name="Mcleish 1992"></ref>). The Corallian strata form the major Jurassic aquifer. The stratigraphy of the Jurassic units is presented in Table 3.1 and Figure 3.1.		During the Jurassic Period Britain was situated between 30 and 40º north of the equator. The warm, humid climate represented a change in climatic regime following the arid Permian and Triassic (Cope, 2006<ref name="Cope 2006">COPE, J C W. 2006. Jurassic: The Returning Seas. 559 in The Geology of England and Wales. BRENCHLEY, P J, and RAWSON, P F (editors). (London: The geological Society.)</ref>; McLeish, 1992<ref name="Mcleish 1992">MCLEISH, A. 1992. ''Geological Science''. (Cheltenham: Nelson Thornes Ltd.)</ref>). Throughout much of the Jurassic, Britain was covered by shallow seas; the sea rises being considered related to the creation of oceanic ridges as the supercontinent Pangaea started to break up (McLeish, 1992<ref name="Mcleish 1992"></ref>). Jurassic sedimentary deposition was hence affected by a series of transgressions and regressions (Allen et al., 1997<ref name="Allen 1997">ALLEN, D J, BREWERTON, L M, COLEBY, L M, GIBBS, B R, LEWIS, M A, MACDONALD, A M, WAGSTAFF, S, and WILLIAMS, A T. 1997. The physical properties of major aquifers in England and Wales. ''British Geological Survey'', WD/97/34 (Keyworth).</ref>). The Jurassic Period is subdivided into three series, Lower, Middle and Upper. The Upper Jurassic series is further subdivided into Oxfordian, Kimmeridgian and Tithonian. The Jurassic rocks in the Vale of Pickering are of Oxfordian age and can be conveniently divided into three divisions based on lithological character. These divisions are the Oxford Clay Formation, the Corallian Group, and the West Walton, Ampthill and Kimmeridge Clay formations (Reeves et al., 1978<ref name="Reeves 1978"> REEVES, M J, PARRY, E L, and RICHARDSON, G. 1978. Preliminary investigation of the groundwater resources of the western part of the Vale of Pickering. Quarterly Journal of Engineering Geology, Vol. 11, 253–262. </ref>). The Upper Jurassic rocks are entirely of marine origin. Marine regression had interrupted eustatic sea-level rise, causing the deposition of the Corallian Group (Powell, 2010<ref name="Powell 2010"> POWELL, J H. 2010. Jurassic sedimentation in the Cleveland Basin: a review. Proceedings of the Yorkshire Geological Society, Vol. 58, 21–72. </ref>). The subsequent re-advance of the sea resulted in the deposition of bituminous clay over the Corallian strata (McLeish, 1992<ref name="Mcleish 1992"></ref>). The Corallian strata form the major Jurassic aquifer. The stratigraphy of the Jurassic units is presented in Table 3.1 and Figure 3.1.

	The Corallian Group is well-developed in north-east England. It mainly comprises ooidal and micritic limestone and calcareous fine-grained sandstone (Powell, 2010<ref name="Powell 2010"></ref>), but also includes a variety of facies from muds, to micritic limestone and oolites, to bioclastic limestones with interbeds of silts and sands (Cope, 2006<ref name="Cope 2006"></ref>; Reeves et al., 1978<ref name"Reeves 1978"></ref>). These facies represent a shallow shelf depositional environment (Allen et al., 1997<ref name="Allen 1997"></ref>) and include a low influx of terrestrial material from the surrounding areas. The absence of debris flows and turbidites suggests that depositional slopes were very low (Hallam, 1992 cited in Allen et al., 1997<ref name="Allen 1997"></ref>). The aquifer crops out in areas including the Hambleton Hills, the Howardian Hills, the Tabular Hills and the North York Moors, forming the northern and south-western boundaries of the Vale of Pickering (Allen et al., 1997<ref name="Allen 1997"></ref>). The Corallian consists of three formations: the Lower Calcareous Grit (formally known as Passage Beds), the Coralline Oolite (formerly known as Coral Rag (Cope, 2006<ref name="Cope 2006"></ref>)) and the Upper Calcareous Grit Formation (Allen et al., 1997<ref name="Allen 1997"></ref>). The 'grit' subdivisions of the Corallian are neither true sandstones, nor true limestones, but are generally fine-grained calcareous sandstones. Both the grits and the oolites vary in lithology but the most marked variations occur in the oolites where reefs are present (Wilson, 1948<ref name="Wilson 1948"> WILSON, V. 1948. East Yorkshire and Lincolnshire. British Regional Geology. (London: HMSO.) </ref>). The Cleveland Basin is an inversion structure and was a major basin of deposition during the Jurassic followed by uplift in the Cretaceous. There are a number of large faults which traverse the area including the Vale of Pickering Fault, the Weaverthorpe Fault and the Coxwold-Gilling- Linton Fault. The throw on the Pickering and Weaverthorpe faults is of the order of 200 m (Allen et al., 1997<ref name="Allen 1997"></ref>).		The Corallian Group is well-developed in north-east England. It mainly comprises ooidal and micritic limestone and calcareous fine-grained sandstone (Powell, 2010<ref name="Powell 2010"></ref>), but also includes a variety of facies from muds, to micritic limestone and oolites, to bioclastic limestones with interbeds of silts and sands (Cope, 2006<ref name="Cope 2006"></ref>; Reeves et al., 1978<ref name="Reeves 1978"></ref>). These facies represent a shallow shelf depositional environment (Allen et al., 1997<ref name="Allen 1997"></ref>) and include a low influx of terrestrial material from the surrounding areas. The absence of debris flows and turbidites suggests that depositional slopes were very low (Hallam, 1992 cited in Allen et al., 1997<ref name="Allen 1997"></ref>). The aquifer crops out in areas including the Hambleton Hills, the Howardian Hills, the Tabular Hills and the North York Moors, forming the northern and south-western boundaries of the Vale of Pickering (Allen et al., 1997<ref name="Allen 1997"></ref>). The Corallian consists of three formations: the Lower Calcareous Grit (formally known as Passage Beds), the Coralline Oolite (formerly known as Coral Rag (Cope, 2006<ref name="Cope 2006"></ref>)) and the Upper Calcareous Grit Formation (Allen et al., 1997<ref name="Allen 1997"></ref>). The 'grit' subdivisions of the Corallian are neither true sandstones, nor true limestones, but are generally fine-grained calcareous sandstones. Both the grits and the oolites vary in lithology but the most marked variations occur in the oolites where reefs are present (Wilson, 1948<ref name="Wilson 1948"> WILSON, V. 1948. East Yorkshire and Lincolnshire. British Regional Geology. (London: HMSO.) </ref>). The Cleveland Basin is an inversion structure and was a major basin of deposition during the Jurassic followed by uplift in the Cretaceous. There are a number of large faults which traverse the area including the Vale of Pickering Fault, the Weaverthorpe Fault and the Coxwold-Gilling- Linton Fault. The throw on the Pickering and Weaverthorpe faults is of the order of 200 m (Allen et al., 1997<ref name="Allen 1997"></ref>).
	<center>		<center>
	{\| class="wikitable"		{\| class="wikitable"
Line 63:		Line 63:
	\|}		\|}
	</center>		</center>

	===Oxford Clay ===		===Oxford Clay ===
	The base of the Oxford Clay marks the start of the Upper Jurassic period in the Vale of Pickering (Powell, 2010<ref name="Powell 2010"></ref>) (Table 3.1). This formation is found below the Corallian facies and consists of grey-green calcareous mudstone and silty mudstone (Powell, 2010<ref name="Powell 2010"></ref>), there is very little variation within these rocks (Reeves et al., 1978<ref name="Reeves 1978"></ref>).		The base of the Oxford Clay marks the start of the Upper Jurassic period in the Vale of Pickering (Powell, 2010<ref name="Powell 2010"></ref>) (Table 3.1). This formation is found below the Corallian facies and consists of grey-green calcareous mudstone and silty mudstone (Powell, 2010<ref name="Powell 2010"></ref>), there is very little variation within these rocks (Reeves et al., 1978<ref name="Reeves 1978"></ref>).

Dbk at 12:55, 10 September 2015

2015-09-10T12:55:14Z

Show changes

Dbk at 12:26, 10 September 2015

2015-09-10T12:26:25Z

← Older revision		Revision as of 13:26, 10 September 2015
Line 3:		Line 3:
	==Regional geology==		==Regional geology==
	===Geological setting===		===Geological setting===
	During the Jurassic Period Britain was situated between 30 and 40º north of the equator. The warm, humid climate represented a change in climatic regime following the arid Permian and Triassic (Cope, 2006; McLeish, 1992). Throughout much of the Jurassic, Britain was covered by shallow seas; the sea rises being considered related to the creation of oceanic ridges as the supercontinent Pangaea started to break up (McLeish, 1992). Jurassic sedimentary deposition was hence affected by a series of transgressions and regressions (Allen et al., 1997).		During the Jurassic Period Britain was situated between 30 and 40º north of the equator. The warm, humid climate represented a change in climatic regime following the arid Permian and Triassic (Cope, 2006<ref nmae="Cope 2006">

			COPE, J C W. 2006. Jurassic: The Returning Seas. 559 in The Geology of England and Wales. BRENCHLEY, P J, and RAWSON, P F (editors). (London: The geological Society.)

			</ref>; McLeish, 1992). Throughout much of the Jurassic, Britain was covered by shallow seas; the sea rises being considered related to the creation of oceanic ridges as the supercontinent Pangaea started to break up (McLeish, 1992). Jurassic sedimentary deposition was hence affected by a series of transgressions and regressions (Allen et al., 1997).

	The Jurassic Period is subdivided into three series, Lower, Middle and Upper. The Upper Jurassic series is further subdivided into Oxfordian, Kimmeridgian and Tithonian. The Jurassic rocks in the Vale of Pickering are of Oxfordian age and can be conveniently divided into three divisions based on lithological character. These divisions are the Oxford Clay Formation, the Corallian Group, and the West Walton, Ampthill and Kimmeridge Clay formations (Reeves et al., 1978). The Upper Jurassic rocks are entirely of marine origin. Marine regression had interrupted eustatic sea-level rise, causing the deposition of the Corallian Group (Powell, 2010). The subsequent re-advance of the sea resulted in the deposition of bituminous clay over the Corallian strata (McLeish, 1992). The Corallian strata form the major Jurassic aquifer. The stratigraphy of the Jurassic units is presented in Table 3.1 and Figure 3.1.		The Jurassic Period is subdivided into three series, Lower, Middle and Upper. The Upper Jurassic series is further subdivided into Oxfordian, Kimmeridgian and Tithonian. The Jurassic rocks in the Vale of Pickering are of Oxfordian age and can be conveniently divided into three divisions based on lithological character. These divisions are the Oxford Clay Formation, the Corallian Group, and the West Walton, Ampthill and Kimmeridge Clay formations (Reeves et al., 1978). The Upper Jurassic rocks are entirely of marine origin. Marine regression had interrupted eustatic sea-level rise, causing the deposition of the Corallian Group (Powell, 2010). The subsequent re-advance of the sea resulted in the deposition of bituminous clay over the Corallian strata (McLeish, 1992). The Corallian strata form the major Jurassic aquifer. The stratigraphy of the Jurassic units is presented in Table 3.1 and Figure 3.1.
Line 10:		Line 14:

	The Cleveland Basin is an inversion structure and was a major basin of deposition during the Jurassic followed by uplift in the Cretaceous. There are a number of large faults which traverse the area including the Vale of Pickering Fault, the Weaverthorpe Fault and the Coxwold-Gilling- Linton Fault. The throw on the Pickering and Weaverthorpe faults is of the order of 200 m (Allen et al., 1997).		The Cleveland Basin is an inversion structure and was a major basin of deposition during the Jurassic followed by uplift in the Cretaceous. There are a number of large faults which traverse the area including the Vale of Pickering Fault, the Weaverthorpe Fault and the Coxwold-Gilling- Linton Fault. The throw on the Pickering and Weaverthorpe faults is of the order of 200 m (Allen et al., 1997).
			<center>
	{\| class="wikitable"		{\| class="wikitable"
	\|+ Table 3.1 Correlation of the formations and members within the Jurassic Corallian Series (adapted from Allen et al., 1997; Cope, 2006; Powell, 2010; Reeves et al., 1978; Wilson, 1948)		\|+ Table 3.1 Correlation of the formations and members within the Jurassic Corallian Series (adapted from Allen et al., 1997; Cope, 2006; Powell, 2010; Reeves et al., 1978; Wilson, 1948)
Line 66:		Line 70:
	\| 20 to 50		\| 20 to 50
	\|}		\|}
			</center>
	===Oxford Clay ===		===Oxford Clay ===
	The base of the Oxford Clay marks the start of the Upper Jurassic period in the Vale of Pickering (Powell, 2010) (Table 3.1). This formation is found below the Corallian facies and consists of grey-green calcareous mudstone and silty mudstone (Powell, 2010), there is very little variation within these rocks (Reeves et al., 1978).		The base of the Oxford Clay marks the start of the Upper Jurassic period in the Vale of Pickering (Powell, 2010) (Table 3.1). This formation is found below the Corallian facies and consists of grey-green calcareous mudstone and silty mudstone (Powell, 2010), there is very little variation within these rocks (Reeves et al., 1978).
Line 73:		Line 77:
	The beginning of the Lower Calcareous Grit Formation is mostly defined by the gradual replacement of the argillaceous conditions of the Oxford Clay deposition with an influx of fine arenaceous material. The lower Calcareous Grit Formation is the same age as the Oxford Clay. The only exception to this is in the south-west part of the Hambleton Hills, where the Lower Calcaerous Grit Formation lies on Middle Jurassic beds, as the Oxford Clay is missing (Cope, 2006; Wilson, 1948; Wilson, 1949).		The beginning of the Lower Calcareous Grit Formation is mostly defined by the gradual replacement of the argillaceous conditions of the Oxford Clay deposition with an influx of fine arenaceous material. The lower Calcareous Grit Formation is the same age as the Oxford Clay. The only exception to this is in the south-west part of the Hambleton Hills, where the Lower Calcaerous Grit Formation lies on Middle Jurassic beds, as the Oxford Clay is missing (Cope, 2006; Wilson, 1948; Wilson, 1949).

	The formation generally comprises fine- to medium-grained calcareous sandstones which attains maximum thickness in the Tabular and Hambleton Hills, thinning southwards and eastwards towards the coast (Allen et al., 1997; Wilson, 1948). Coastal sections have shown exposed Lower Calcareous Grit Formation divided into three units. The upper unit is known as the ~~“Ball Beds”~~ and is ~~3 – 5~~ m thick. The ~~“Ball Beds”~~ comprise very ferruginous sandstone containing large, gritty, fossiliferous calcareous concretions. A hard grey siliceous sandstone ~~1 – 2~~ m thick underlies the ~~“Ball Beds”~~. The lower unit is ~~12 – 14~~ m thick and comprises thickly bedded sandstone with siliceous cement. The cement is frequently concentrated into small masses which weather out in irregular nodular bands (Wilson, 1948).		The formation generally comprises fine- to medium-grained calcareous sandstones which attains maximum thickness in the Tabular and Hambleton Hills, thinning southwards and eastwards towards the coast (Allen et al., 1997; Wilson, 1948). Coastal sections have shown exposed Lower Calcareous Grit Formation divided into three units. The upper unit is known as the 'Ball Beds' and is 3–5 m thick. The 'Ball Beds' comprise very ferruginous sandstone containing large, gritty, fossiliferous calcareous concretions. A hard grey siliceous sandstone 1–2 m thick underlies the 'Ball Beds'. The lower unit is 12–14 m thick and comprises thickly bedded sandstone with siliceous cement. The cement is frequently concentrated into small masses which weather out in irregular nodular bands (Wilson, 1948).

	[[Image:OR/15/048 fig3.1.jpg\|thumb\|center\|400px\| Figure 3.1 Geology in and around the Vale of Pickering.]]		[[Image:OR/15/048 fig3.1.jpg\|thumb\|center\|400px\| Figure 3.1 Geology in and around the Vale of Pickering.]]

Dbk: /* Current issues in groundwater quality */

2015-09-04T13:17:07Z

Current issues in groundwater quality

← Older revision		Revision as of 14:17, 4 September 2015
Line 250:		Line 250:

	Source protection zones (SPZs) around boreholes have been identified by the EA (Figure 3.2). These show the risk of contamination from activities which may cause pollution. They are zoned according to the risk in terms of time for the pollution to travel to the borehole and extent of the contamination risk. Within the Corallian large SPZs are located around Pickering, Scarborough and East Ness. Local SPZs (~500m in diameter) are sparsely distributed around the periphery of valley bottom, within the Hambleton and Howardian Hills, and in the area south of Malton (EA, 2015).		Source protection zones (SPZs) around boreholes have been identified by the EA (Figure 3.2). These show the risk of contamination from activities which may cause pollution. They are zoned according to the risk in terms of time for the pollution to travel to the borehole and extent of the contamination risk. Within the Corallian large SPZs are located around Pickering, Scarborough and East Ness. Local SPZs (~500m in diameter) are sparsely distributed around the periphery of valley bottom, within the Hambleton and Howardian Hills, and in the area south of Malton (EA, 2015).

			==References==


	[[category:OR/15/048 Baseline groundwater chemistry: the Corallian of the Vale of Pickering, Yorkshire \| 05]]		[[category:OR/15/048 Baseline groundwater chemistry: the Corallian of the Vale of Pickering, Yorkshire \| 05]]