part 3] 



L<ESS, ETC. OF THE DURHAM COAST. 



193 



Diversion of the ice-sheet coming over the Stainmoor Gap 

 down the Vale of York, and formation of the main Boulder- | 

 Clay of the Durham coast by the ice-sheet which swept 

 past and partly across the Cheviots southwards and south- 

 westwards towards the northern face of the Cleveland Hills. 

 This sheet held up the lakes in the valleys of Cleveland. A 

 lobe of ice at the same time crossed the Tyne Gap, and was 

 ■diverteil southwards west of and parallel to the Cheviot ice. 



Possible Interglacial Interval (r). 



The ice which crossed Stainmoor Gap passed directly [- 

 eastwards out to sea down the Tees valley, and deposited 

 the stony Boulder-Clays which fill an old depression (due to 

 solution of anhydrite) at Hartlepool : these deposits have 

 only been seen during dock excavations, and contain none 

 but western erratics. This ice-stream carried the Shap 

 granite-boulders, the northern limit of which in Durham 

 is well defined. 



At the same time a similar sheet crossed the Tyne Gap, 

 and passed out to sea down the Tyne valley, cariying Lake- 

 District rocks, which were later caught up by the Cheviot 

 ice and incorporated in the Main Drift of the Durham coast. J 



Interglacial Episode. 



Possible erosion of many of the valleys in Durham 

 hitherto called Preglacial, which were filled in later by 

 matcrial carried by the local ice- sheets. 



Probable formation of beaches on the east coast which 

 yielded the shells and flints found in the Cheviot Drifts. 



Weathering and rotting of Scandinavian boulders lying j 

 near the surface of the loess and Scandinavian Drift at 

 Warren- House Gill. Decalcification of the loess. 



Deposition of loess overlying part of the Scandinavian I 

 Boulder-Clay at Warren- House Gill, and partial redeposition 

 of the upper layers of the loess by water. i 



Deposition of the main Scandinavian Drift which fills up \ 

 the Preglacial depression of Warren - House Gill with 

 slickensided grey and brown shelly clay containing Nor- 

 wegian stones, fragments of Chalk, and local Permian 

 material. Parts of this clay are mixed witli loess, showing 

 that the advance was irregular and intermittent, also that 

 loess was deposited round the fringe of the ice-sheet as it 

 advanced, and was overridden and caught up by it. 



The fringe of the advancing Scandinavian ice- sheet tore 

 up the red and grey marls and peaty freshwater deposits 

 containing shells and plants which lay in its path, and thrust 

 them into numerous hollows and fissures in the Magnesian 

 Limestone which lay open in front of it. The transported 

 material was strongly slickensided in the process. 



Deposition of part of the freshwater shelly clays with^ 

 seeds, trees, mammalian bones, etc. at some point east of | 

 the present coast-line, which were caught up later by the [■ 

 advancing ice-sheet. 



Deposition of freshwater clays with seeds of a pre- 

 Cromerian flora east of the present coast-line, upon Permian 

 red and green spotted marls. 



Maximum 



or THE 



Local 



British 



Glaciation. 



INTERGLACIAL. 



Second 



AND 



Maximum 



Advance 



of THE 



Scandinavian 



Ice-Sheet. 



CaOMEBIAH 



or First 



Intergi. \. I \L 



OF THE 



Continent. 

 Teolian. 



