Vol. 60.] SECTIONS IX THE BRISTOL DISTRICT. 181 



the wide distribution of the conglomerates. It was not 

 along a beach or shore-line that these beds were deposited : that is 

 to say, they do not form a narrow band between a shore of older 

 formations and a deep Rhaetic sea, for they do not occur along any 

 single line. Xothing is more striking than the widespread character 

 of the deposit. Then, again, at Penarth and elsewhere the Bone-Bed 

 lies in pockets of a contemporaneously-eroded surface of hard, tea- 

 green, calcareous marl. In many localities that marl was firm 

 enough to be rolled into balls. Lee noticed ' rills on the Marl ' at 

 Gold Cliff (35). At Lavernock Point the Bone-Bed fills sun-cracks 

 in the marl (35): here, then, must have been extensive sun-dried 

 flats, which were overflowed by the sea that laid down the Bone- 

 Bed. There are ripple-marks in it at Wainlode Cliff (51). From 

 this facies there is every gradation to that in which no con- 

 glomerate at all is to be found, but only a few scales and teeth, 

 or not even that. Here, of course, the water was somewhat deeper, 

 perhaps several fathoms : probably these deeper parts were of the 

 nature of channels and pools. 



I conclude, then, that at the time when the Rhaetic Bone-Bed 

 was laid down, the great Keuper lake had been nearly dried up in 

 some localities, or silted up in others. The shallower parts had 

 been left as muddy flats a few inches above water-level, the deeper 

 parts as very shallow and extensive lagoons, of course highly saline, 

 and connecting these were occasional deeper channels or pools. 

 The exposed flats were rippled and sun-cracked. Then the sea 

 entered from the German area, and along certain of the channels a 

 Rhaetic fauna spread. 



II. At a period when the conditions were such as those just 

 described, and shortly after the Rhaetic sea had entered, but before 

 it had done more than freshen and send its fauna into some of the 

 main channels, into a set of which it had gained access, came a 

 period of rough weather. 



The points in favour of regarding the Rhaetic Bone-Bed as a 

 storm-deposit are as follows : — 



It was not due to the first inrush of the Rhaetic sea, for that had 

 already entered. 



It was due to a cause operative over the whole of England, and, 

 probably at the same time, over part of the Continent. 



It resulted in the overflowing of dry flats a little above water- 

 level. 



The movements were such as to scatter pebbles, roll fragments of 

 marl, break bones and teeth that were large, and often round off 

 the smaller ones. 



For some reason the cause that determined this conglomerate- 

 bed also determined the death of immense numbers of fishes, their 

 disintegration, and the scattering of their remains far and wide. 

 But in certain localities, presumably where the water was deeper, 

 these results did not take place, consequently the fishes were not 

 killed, and the water at the bottom was not so disturbed as to 

 lay down a conglomerate. 



