256 A HISTORY OF L0N6RIDGE. [Chap. 12. 



besides being less exposed to denudation, were in many instances 

 buried beneath, a protective covering of detritus worn from the high 

 lands. 



Thus it is we find our coal-measures occurring in isolated synclinal 

 areas, which represent the ancient valleys. Our district then formed 

 part of the high exposed land. The coal-measures, together with a 

 few of the underlying beds, have been removed by denudation, leaving 

 the older rocks exposed to view. 



If the British area had been simply upheaved, and not puckered 

 into hiU and valley, after the deposition of the coal-measures, there 

 would not now remain a vestige of coal in our land. The whole 

 would have been removed by the action of the meteorological forces 

 during the ages that have lapsed since the coal was formed. 



When we consider all that coal has done for Britain, and aU that 

 would happen if even now our supply were to fail, we have reason to 

 be thankful that our country has not always been so free from sub- 

 terranean disturbance as it is at present. 



SEOONDABY K0CK8. 



The sole representative of these rocks in our district is the Pebble 

 Beds of the Bunter, almost the oldest of the Mesozoic formations. It 

 occurs in a large tract from Myerscough in the north-west, to Bamber 

 Bridge in the south-east, and includes Grimsargh and Penwortham in 

 its shorter diameter. 



The rocks are practically unfossiliferous if we except the fossils of 

 older rocks occasionally found in the pebbles. These are sometimes of 

 well known species, and lead to the identification of the rock from 

 which the pebble was worn. The Bunter is celebrated for its water- 

 bearing properties. In fact it is said that boring for water in these 

 rocks has never proved unsuccessful. 



During the deposition of the newer mesozoic rocks our district had a 

 varying fortune of land and sea area, but whatever deposits occurred 

 they were subsequently removed by denudation. 



TERTIARY ROCKS. 



These are tmrepresented in this district. Land prevailed probably 

 over the whole of the north of the British area. 



