20 president's address. 



and of Lower Kimmeridge clay near Biggleswade. 1 These also probably 

 have not travelled more than a few miles. But others of smaller size 

 have often made much longer journeys. The boulder clays of Eastern 

 England are fall of pieces of rock, commonly ranging from about half an 

 inch to a foot in diameter. Among these are samples of the carboniferous, 

 Jurassic, and cretaceous rocks of Yorkshire and the adjacent counties; 

 the red chalk from either Hunstanton, Speeton, or some part of the 

 Lincolnshire wolds, being found as far south as the northern heights of 

 London. Even the chalk and flint, the former of which, especially in 

 the upper boulder clay, commonly occurs in well-worn pebbles, are 

 frequently not the local but the northern varieties. And with these 

 are mingled specimens from yet more distant sources — Cheviot 

 porphyrites, South Scottish basalts, even some of the crystalline rocks 

 of the Highlands. Whatever was the transporting agent, its general 

 direction was southerly, with a slight deflection towards the east in 

 the last-named cases. 



But the path of these erratics has been crossed by two streams, 

 one coming from the west, the other from the east. On the western 

 side of the Pennine watershed the Shap granite rises at "Wasdale Crag 

 to a height of about 1,600 feet above sea-level. Boulders from it have 

 descended the Eden valley to beyond Penrith; they have travelled in 

 the opposite direction almost to Lancaster, 2 and a large number of them 

 have actually made their way near the line of the Lake District water- 

 shed, across the upper valley of the Eden, and over the high pass 

 of Stainmoor Forest, 3 whence they descended into Upper Teesdale. 

 Subsequently the stream seems to have bifurcated, one part passing 

 straight out to the present sea-bed, by way of the lower course of the 

 Tees, to be afterwards driven back on to the Yorkshire coast. The 

 other part crossed the low watershed between the Tees and the Ouse, 

 descended the Yale of York, and spread widely over the plain. 4 Shap 

 boulders by some means penetrated into the valleys tributary to the Ouse 

 on its west bank, and they have been observed as far to the south-east 

 as Eoyston, near Barnsley. It is noteworthy that Lake District rocks 

 have been occasionally recorded from Airedale and even the neighbour- 

 hood of Colne, though the granite from Shap has not been found there. 

 The other stream started from Scandinavia. Erratics, some of which 

 must have come from the north-western side of the Christiania Fjord, 

 occur on or near the coast from Essex to Yorkshire, and occasionally 



1 H. Home, Quart. Journ. Geol. Soc, lix. (1903), p. 375. 



2 A pebble of it is said to have been identified at Moel Tryfaen. 



8 The lowest part of the gap is about 1,400 feet. A little to the south is another 

 gap about 200 feet lower, but none of the boulders seem to have taken that route. 



4 A boulder was even found above Grosmont in the Eske valley, 345 feet above 

 sea-level. 



