September 9, 1910] 



SCIENCE 



335 



also probably have not traveled more than 

 a few miles. But others of smaller size 

 have often made much longer journeys. 

 The boulder clays of eastern England are 

 full of pieces of rock, commonly ranging 

 from about half an inch to a foot in diam- 

 eter. Among these are samples of the car- 

 boniferous, Jurassic and cretaceous rocks 

 of Yorlcshire 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, espe- 

 cially 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 por- 

 phjTites, South Scotch basalts, even some 

 of the crj'stalline 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 

 traveled in the opposite direction almost to 

 Lancaster,"" and a large number of them 

 have actually made their way near the line 

 of the Lake District watershed, across the 

 upper valley of the Eden, and over the high 

 pass of StainmOor Forest,"^ whence they 



"A pebble of it is said to have been identified 

 at Moel Tryfaen. 



" 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. 



descended into Upper Teesdale. Subse- 

 quently the stream seems to have bifur- 

 cated, 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 Vale of York 

 and spread widely over the plain.'- Shap 

 boulders by some means penetrated into the 

 valleys tributary to the Ause on its west 

 bank, and they have been observed as far 

 to the southeast as Royston, near Bamsley. 

 It is noteworthy that Lake District rocks 

 have been occasionallj- recorded from Aire- 

 dale and even the neighborhood 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, oc- 

 cur on or near the coast from Essex to 

 Yorkshire, and occasionally even as far 

 north as Aberdeen, while they have been 

 traced from the East Anglian coast to near 

 Ware, Hitchin and Bedford.'" It may be 

 important to notice that these Scandi- 

 navian erratics are often waterworn, like 

 those dispersed over Denmark and parts of 

 northern Germany. 



On the western side of England the 

 course of erratics is not less remarkable. 

 Boulders from southwestern Scotland, es- 

 pecially from the Kirkcudbright district, 

 both waterworn and angular, are scattered 

 over the lowlands as far south as Wolver- 

 hampton, Bridgnorth and Church Stretton. 

 They may be traced along the border of 

 North Wales, occurring, as has been said, 

 though generally small, up to about 1,300 

 feet on Moel Tryfaen, 1,100 feet at Gloppa, 



"A boulder was even found above Grosmont in 

 the Eske valley, 345 feet above sea-level. 



^ R. H. Kastall and J. Romanes, Quart. Journ. 

 Gcoh Soc, LXV., 1909, p. 246. 



