CHAP. VIII.] TEIASSIC PERIOD. 121 



know, be exposed beneath the Trias in the south of Derby- 

 shire. 1 Quartz and quartzite are exactly the rocks which 

 would survive long transportation and repeated transference 

 from one formation to another, in which process the more 

 destructible Scotch rocks would be destroyed. 



We must therefore confess that our present knowledge 

 does not enable us to arrive at any definite conclusion as 

 to the exact position of the strata from which the pebbles 

 of the Bunter conglomerates were derived. It is certain, 

 however, that, whether they came from the north or the 

 south, they can only have been distributed over the area 

 they now occupy by the action of strong currents. What 

 currents these can have been will be discussed in the 

 sequel. 



Coming next to the Keuper, or Upper Triassic beds, we 

 find that these have a much wider extension than the 

 Bunter beds. There is generally a certain amount of un- 

 conformity between the two divisions, the surface of the 

 Bunter being often uneven and eroded, and the base of the 

 Keuper in the Midland counties being always a breccia, 

 pebble bed, or conglomerate. Over this base there are red, 

 yellow, and white sandstones, and these are succeeded by 

 flaggy sandstones and sandy marls passing up into red 

 marls with beds of rock-salt and gypsum. 



The Lower Keuper sandstones are generally soft and 

 fine-grained, often micaceous and laminated, and frequently 

 current-bedded. There are, however, some beds of coarser 

 sandstone with worn and rounded grains, which may have 

 been wind-borne sands. The red and brown flaggy sand- 

 stones, which are generally known as " the waterstones," 

 exhibit clear signs of having been deposited in the shallow 



1 It is more likely perhaps that the exposures of the Carboniferous 

 pebble beds lay more to the south-east, beneath Northampton and 

 Huntingdon, as 1x5 wer Carboniferous sandstones occur beneath the 

 Trias near Northampton. 



