THE BUILDING OF THE DERBYSHIRE LIMESTONE. 227 



and its beach may be traced at intervals on the eastern sides of 

 the liills of the west of Ireland. From here it stretched eastwards 

 across England, for a distance of 750 miles, into what is 

 now Holland, Belgium, North France, and the valley of the 

 Rhine. To the north-west lay a great continent, to which 

 Professor Dawkins has given the name Archaia, from the fact 

 that it was mainly composed of archaian rocks ; and 

 on the shores of this ancient continent our mountain limestone 

 was deposited. " The hills of Down, and the Wicklow mountains, 

 were islands, the latter, not improbably, being connected with 

 Wales, across what is now the Irish Sea, while the higher 

 ranges in the Isle of Man and the Highlands of Scotland 

 stood over the sea, between the island of Mayo and the island 

 of Cumbria." * 



After a time a shallowing of this ancient carboniferous sea 

 took place, for we find, overlying the limestone, the series of 

 shales and sandstones known as the Yoredale Rocks. Further 

 shallowing, with the accumulation of the Millstone Series, and 

 finally a land surface, upon which grew the luxuriant vegeta- 

 tion of the Coal Measures, and which underwent numerous 

 oscillations of level with the successive accumulations of 

 vegetable matter which gave rise to our coal seams. 



* Professor W. B, Dawkins. 



