CHAP. XIV.] SUMMARY OF GEOGRAPHICAL EVOLUTION. 305 



which is so ancient as to be different from any previously 

 known, and who is endeavouring to restore the ground- 

 plan of the original building from the scanty fragments 

 which remain ; he observes a piece of wall here, a corner 

 of masonry there, a broken arch in one place, and a pros- 

 trate column in another ; he has to consider the probable 

 relations of these remnants to one another, and to evolve 

 a connected whole by imagining the position of the missing 

 parts. So the geologist finds indications of dry land in 

 one place, of deep sea in another, of an island here, and of a 

 long coast-line elsewhere, and he has to piece the puzzle 

 together and to supply the missing connections as best he 

 can with the knowledge at his command. 



At present, therefore, the maps of early Palaeozoic geo- 

 graphies are only pictorial representations of the ideal 

 views which are suggested to our minds by the inferences 

 obtained from the study of a few small and disconnected 

 areas. This is more particularly the case with the geo- 

 graphical restorations of Cambrian, Ordovician, Silurian, 

 and Devonian times ; that of the Carboniferous period 

 does, indeed, stand on a wider and more trustworthy basis, 

 because various circumstances have contributed to put us 

 in possession of a more complete record of this period than 

 we have of those which preceded it, and we did therefore 

 pause to attempt a more detailed reconstruction of the 

 geography of the British region during the formation of 

 the Carboniferous Limestone. We may, perhaps, assume 

 that the restoration given in Plate IY. is so far approxi- 

 mately correct as to show the real connections of the seas 

 and the general outlines of the land areas of the period in 

 question. 



We can, at any rate, say that certain districts which 

 form part of modern Britain were also portions of the 

 early Carboniferous land, and that they were then struc- 

 turally the same as they are now, so that as rock-masses 



x 



