254 A HISTORY OF LONGRIDGE. [Chap. 12. 



one. Large continents suggest large rivers. The warmth of the 

 Carboniferous sea would give rise to rapid evaporation and produce a 

 copious rainfall. This, again, suggests rapid denudation. 



Examination of the grits shows them to be made up of quartzose 

 particles, not much water-worn, with the interstices filled with felspathic 

 matter. The original rocks must therefore have contained these two 

 minerals in large proportions. Such rocks are Granite, Gneiss, and 

 Pegmatite, all of which are included in the term " granitic." 



The Millstone Grits have yielded but few fossils, and these are 

 mostly land plants. This, of course, is in itself evidence of the prox- 

 imity of land. The Lower Millstone Grit occurs on the southern flank 

 of the Longridge Fell. The beds have a general dip to the south-east 

 about fifteen degrees from the horizontal. 



The Millstone and Yoredale Grits resist denudation in a remarkable 

 manner. At the same time the soils derived from them are wet and 

 unproductive. We thus find them forming hilly country usually 

 covered with peatj' bogs or wild moorlands. Among their good 

 qualities may be mentioned the steady yield of good water, and an 

 almost unlimited supply of good building stones. As an example of 

 the latter may be mentioned that for which Longridge is so justly 

 famous. 



THE COAL MEASTIEES. 



These beds do not occur in the district, but the better to account for 

 their absence it will be well to give here a short account of their forma- 

 tion. 



The deposition of the Millstone Grit completely shallowed the Car- 

 boniferous Sea. The whole area became gradually silted up, forming 

 a series of extensive marshes. 



A period of quiescence now set in, during which a luxuriant and 

 truly tropical vegetation sprang up and accumulated on the marshy 

 ground. Giant Lopidodendrons, Sigillarias, and Calamites, reared 

 their lofty heads above more humble conifers and delicate ferns, while 

 yet the land was scarcely above the sea level. 



After this peaceful state had continued sufficiently long to allow an 

 accumulation of several feet of vegetable matter, depression set in and 

 estuarine conditions again prevailed. This was succeeded by another 



