Conglomerates, and Marls of Devonshire. 
35 
Sandstones east of Exmouth, nothing of the kind has been met 
with, so far as I am aware, except at Watcombe, where they are 
numerous. 
Except where interstratified Sandstones occur, it is commonly 
very difficult to resolve the Marl into an}i:hing like regular beds. It 
presents itself under the most fragmentary aspect, and suggests the 
thought that it has undergone considerable shrinkage, for the entire 
cHft' sometimes appears to be built up of rudely ellipsoidal nodules, 
from the size of hazel nuts to masses upwards of a foot in diameter. 
The dislodgement of one of these generally brings down a large 
number which almost invariably exfoliate, giving off shell after shell 
each of which breaks into angular pieces. Though denominated 
Marl it does not contain much carbonate of lime, nor is it frequently 
entirely destitute of this substance. 
In my last lecture I stated that a doubt existed respecting the 
place of the Red Rocks of Devonshire in the chronological series 
of the geologist, and endeavoured, from new data, to prove that 
they belonged to the age of the Lower Trias, commonly termed 
the Bunter. A part only of the doubt was then removed ; that is to 
say the question has been put " Do the Marls beyond the mouth 
of the Exe belong to the same period, or subdivision of period, as 
the Conglomerates and Sandstones south of the same river'? " To 
this question, which has been recently pressed on my attention by 
Sir R. I. Murchison, I hope a reply can now be given. 
Marl — though certainly in sparing quantities — is found inter- 
stratified with the two other classes of rocks throughout the district 
south of the Exe. A well-marked bed occurs in the north cliff at 
Goodrington Sands, Torbay (see h. fig 1.); that is, excepting the 
outliers, the southern verge of the formation. It occurs, also, near 
Paignton Harbour, at the Corbons, at Dawlish and elsewhere ; and is 
eveiy^vhere characterized by the tendency — already mentioned — to 
break into rudely ellipsoidal nodules. Moreover, much of the paste 
of the Conglomerate is a mixture of Sand and Marl, and this is the 
case in a marked degi-ee between the Teign and Exe, that is with 
increased proximity to the true Marl district. Add to this the fact 
that the Conglomerates on each bank of the Exe — at Langstone 
Point and at Exmouth — consist of much finer material than further 
south, and we have a sort of prediction of the coming change — the 
withdrawal of all detritus large enough to be called stones, and the 
surrender, to Sand and Marl exclusively, of the new area into which 
the deposits were to be carried. 
The most conclusive evidence on the point, however, occurs in the 
UndercHff, known as the "Plantation," below, and east of Beacon 
Ten-ace, at Exmouth ; where the Marl is found lying conformably 
on the Conglomerate, the upper surface of the latter presenting 
nothing like denudational inequalities, nothing, in fact, to mark 
non- sequent succession ; no indication whatever of an interval of 
