of the Older Stratified Rocks of Devonshire and Cornwall. 2i3 



press purpose, among others, of inquiring into this point, re- 

 visited the country last summer, but was not able to discover 

 any discordance in the junction south of Barnstaple: on the 

 contrary, the culmiferous deposits seemed rather to be a con- 

 tinuous uninterrupted series, following the older rocks. Now, 

 if this be so, one of two things must follow. Either the culm 

 measures must be older, or the rocks of North Devon younger, 

 than we had at first supposed. The question then is this, 

 what is the evidence given by the fossils ? The fossil plants 

 of the culm beds are undistinguishable from those of Pem- 

 brokeshire, the nearest coal field, while certain shells of the 

 black limestone, subordinate to the lower culm strata, prove 

 also to be undistinguishable from species which occur in the 

 true carboniferous system ; and thus we have on fossil evi- 

 dence every ground for believing that our first view respecting 

 the culm measures was correct, and that they are the true 

 equivalents of the carboniferous system. 



On re-examining, however, the collections of fossils we had 

 made among the strata which lie beneath the northern edge 

 of the culm field, we have seen reason to change our views 

 respecting the age of these older rocks. 



In the uppermost of the five groups into which we pro- 

 visionally divided those rocks, we now find no unequivocal 

 lower Silurian fossils: for though two distorted casts have 

 much the appearance of shells of that date, there are other 

 and better preserved specimens, which approach so near to 

 species known in the carboniferous limestone, {^pirifer ciispi- 

 datus and Spirifer attenuatus) as to be almost undistin- 

 guishable from them ; and with these are found Leptcena:, 

 having somewhat the character of upper Silurian fossils, and 

 undescribed Terebratulce, together with Trilobites, some of 

 entirely new forms, and others approaching to upper Silurian 

 types. 



Below these slaty and calcareous strata near Barnstaple, a 

 part of which we first mistook, as above stated, for Caradoc 

 sandstone*, are the sandstones of Baggy Point, Marwood, and 

 Sloley, which we have elsewhere described in detail. In the 

 line of these are found certain fossil plants, specimens of which 

 were first sent to us by Major Harding, and others were laid 

 before the Geological Society by the Rev. D. Williams : some 

 of them are considered by Mr. Williams and Mr. De la Beche, 

 on the authority of Dr. Lindley, to be undistinguishable from 



• The stronj; resemblance of the Caradoc sandstone, in consequence of 

 mineral character and the circular marks ofcrinoidal stems, to the sand- 

 stone*- of tlie lower siiale oCthc Carboniferous linicstonr, and the probabijity 

 that this rcscndjlaiicc would lead tomistakeb, has already been pointed out 

 by one of the auilmrs. (Silurian System, pp. '.\SA,Ah',\.) 



112 



