60 PALEOZOIC TIME. [CHAP. V. 



rather than an estuary. The nature of the deposits would 

 depend entirely on the character of the rocks which form 

 the neighbouring land, and it is evident that this land 

 must have consisted largely of granitoid, felspathic, and 

 quartziferous rocks, and though some of the material 

 doubtless came from the western side, yet it seems pro- 

 bable that the larger proportion came from the eastern. 

 We have seen that land-tracts formed in part of such rocks 

 lay over central England in Silurian times, and the 

 Devonian upheaval doubtless greatly extended their boun- 

 daries, especially toward the east and the north. 



We have no evidence as to the direction of the inlet 

 further northward, but it probably narrowed, and may 

 have received the waters of a river that drained the land to 

 the north and east. In the north-west of England and in 

 the Isle of Man there is a great unconformity between the 

 older Palaeozoic rocks and the Carboniferous, so that it is 

 inferred that all the north of England was land. 



Parts of Scotland were also dry land, and the earth- 

 movements in this region seem to have resulted in the for- 

 mation of several mountain ranges having a north-east and 

 south-west direction, between which ranges were low-lying 

 tracts that were at first inlets of the sea, but by the con- 

 tinued elevation of the land were apparently converted into 

 large inland lakes. 



Dr. Arch. G-eikie considers that the four areas of Old 

 Bed Sandstone, mentioned on p. 51, were distinct and 

 separate basins of deposit, at any rate during the earlier 

 half of the period ; l that they were also disconnected from 

 the sea, and formed large inland lakes. He has, therefore, 



1 The great thickness of material in them would be more easily under- 

 stood if they lay between lofty mountain ranges, for they find a parallel 

 in the Siwalik group of India, and the manner of their formation is illus- 

 trated by deposits in the upper basin of the Indus. See Drew in 

 " Quart. Journ. Geol. Soc.," vol. xxix. p. 441. 



