Rhcztic Beds. 159 



St. Cassian and Hallstatt beds are believed by Hauer 

 and Suess to represent the same strata ; that is to say, 

 they are the ocean representatives of the red marls of 

 England and other parts of Europe, which I described 

 as having been deposited in large inland salt lakes. 

 The Rhcetic beds of England, which merely represent 

 the very topmost part of the Italian series, seem to 

 have been deposited in shallow seas and estuaries, or 

 in lagoons or occasional salt lakes of small size, now 

 and then separated from the sea by minor accidental 

 changes in physical geography. 



On the north shore of the estuary of the Severn, at 

 Penarth, near Cardiff, 1 and elsewhere in England, there 

 is a perfect physical gradation between the New Eed 

 Marl and the Rhaetic Beds, shown by interstratifications 

 of red, green, and grey marls, which, varying in different 

 areas, pass upward by degrees into limestones, sand- 

 stones, and black shales. It is, therefore, impossible 

 always to determine in this series precisely where the 

 New Ked Marl ends and the Rhsetic Beds begin ; and, 

 indeed, all through the Red Marl, from bottom to top, 

 there is a tendency to a recurrence of interstratified 

 deposits that, lithologically, closely resemble the lower 

 parts of the Rhsetic beds, as, for example, at Penarth, 

 near Cardiff. The ' White Lias ' of Lyme Regis is now 

 classed with this subformation. 



All over England, wherever the base of the Lower 

 Lias is well seen, the Rhaetic beds, rarely more than 50 

 or 100 feet thick, are found to lie between the Lias and 

 the New Red Marl. As a general rule they are seen to 

 pass conformably and by easy gradations into each other, 

 and they were, indeed, always classed with the Lias, till 

 separated from these strata bf Oppel. 



1 The Rhsetic strata are sometimes called the Penarth Beds. 



