@6 



Mr. De la Beche on the Lias of the Coast, 



On the west of the fault in Pinhay Bay the limestones are thrown down 

 about the thickness of the great bed of white lias ; the dark marl beneath 

 that bed, on the east of the fault, being in a line with the upper part of the 

 white lias on the west of it : but after being thus thrown down, the strata 

 rise again towards the west, so that the upper beds of the subjacent red marl 

 emerge from beneath them near Humble Rock. Between that place and Cul- 

 verhole Point the lias beds come down again to the level of the shore, and are 

 there visible, for the last time on this part of the coast, above the red marl. 



III. The beds which occur between the white lias limestones and the upper 

 light blueish-green beds of the marl belonging to the new red sandstone for- 

 mation, and which complete the section of the lias, are best exposed at Culver- 

 hole Point, under Dowlands. — They are as follow : 



Section of the Lower Marl beds of the Lias, at Culverhole Point. 



Dark marl 



Earthy dark grey limestone 



Dark grey slaty marl 



Irregular light grey limestone 



Dark slaty marl 



Compact grey limestone . 



Thickness, 





Thickness, 



Ft. In. 



Ft. In. 



. 3 



Dark slaty marl ; which rests imme.~ 





. 10 



diately on the light blueish-green 





. 5 



beds belonging to the upper part 



> 7 



. 10 



of the new red. sandstone for- 





. 1 4 



mation .....__ 





. 10 







From the sections above given it would appear, that the lias formation in 

 the vicinity of Lyme Regis consists of an alternation of more than seventy- 

 two beds of limestone, with an equal number of marl beds, amounting together 

 to about one hundred and ten feet in thickness, and surmounted by about 

 five hundred feet of marl. 



IV. The lias limestones in the vicinity of Lyme contain numerous organic 

 remains, among which those of the Ichthyosaurus and Plesiosaurus are the 

 most remarkable ; and these are found principally in the marls alternating with 

 the limestones. The characteristic fossils of the lias, — as the Gryphaea incurva. 

 Ammonites Bucklandi, and Plagiostoma gigantea, are by no means uncommon 

 here, and most generally occur in the limestone beds. 



The following is a list of the fossils found in the lias formation, generally, 

 of this neighbourhood : 



