194 TKANSACTIONS OF SECTION C. 



proved to be the oldest sedimentary series. The Keewatin rocks, essentially 

 schists and greenstone?, represent, for the most part, submarine lava flows. 

 On the surface of these flows were deposited the Grenville sediments. While 

 the major part of the Grenville is later than the major part of the Keewatin, 

 a minor part of one group is contemporaneous with a minor part of the other. 

 It is remarkable that among the oldest series of Australia, India, Africa and 

 other countries are rocks that resemble very closely the Keewatin of Canada, 

 with its associated iron formation or jaspilyte. 



Among most of the workers on the pre-Cambrian of North America there 

 i.s now g€neral agreement as to the age relations of the rocks, but different 

 classifications and nomenclatures are employed. Most authors make a dual sub- 

 division of the pre-Cambrian which seems to the author to be purely arbitrary 

 and based on a misconception. There is no proof that the unconformity at 

 the base of the Timiskamian is of less magnitude than that at the base of the 

 Animikean, or vice verm. 



2. The Correlation of the Devonian Rocks of North Devon with iliuse 

 of other localities. By Dr. John W. Evans, F.R.S. 



The Dartmouth Slates of South Devon and Cornwall, which corres.pond, it 

 would seem, to the Schistes d'Oignies of the Ardennes, are not seen in North 

 Devon, but may be concealed by later rocks and be represented in South Wale.'* 

 and the Welsh' Border by the Red Marls of the Lower Old Red Sandstone. It 

 is possible that the Foreland Grits are a local Tacies of the upper portion of 

 the Dartmouth Slates, just as the arenaceous Cosheston Group is a local develop- 

 ment of the upper part of the Red Marls. Both the Foreland Grits and the 

 Cosheston Group appear to have yielded the typical Old Red Sandstone plant 

 Psilophyton. 



[Note. — The author is not inclined to accept the view that the Foreland Grit.s 

 are identical with the Hangmans Grits, which are repeated by faulting.] 



The usual correlation of the Lynton Beds with the Meadfoots of South 

 Devon seems well founded. The lower beds with Pteraspis may be compared 

 with the Schistes de Saint Hubert of the Ardennes, with Spirifer ■primcevius 

 and Pternsjiic (/»»efl.??.?, and the Schistes a Ptera.'ipis diinensis in the Pas de 

 Calais. The Senni Beds, which overlie the Red Marls on the north of the '^outh 

 Wales Coalfield, and contain Pteraspis and Cephalaspis, may be of the same 

 age. The two strata as mentioned have not, lup to the present, yielded any 

 marine forms. 



The Hangmans Grits represent a great thickness of arenaceous beds of the 

 Old Red Sandstone type overlying the Lynton Beds Little is known of the 

 lower portion, but the upper beds include lacustrine or fluviatile beds, with 

 plant remains which are probably referable to the Middle Devonian plant P.<^ilu- 

 phyion. These are succeeded by marine beds with several fossiliferous horizons, 

 some of which have yielded Strhujocephalus. The upper part at least of the 

 Hangmans Grits must therefore be considered to be of Givetian age — that is to 

 say, Upper-Middle Devonian, instead of Upper-Lower Devonian, according to the 

 usiual correlation. This view is supported by the discovery (after the reading of 

 the paper) in the plant-bearing beds of a fish-plate referred by Dr. Smith Wood- 

 ward to Cocrosteus, a genus which is usually of Middle Old Red Sandstone and 

 Middle Devonian age, though it has been found in the Upper Old Red Sandstone. 

 The Staddon Grits of South Devon, on the other hand, which are usually con- 

 sidered to be the equivalent of the Hangmans Grits, cannot extend upwards much 

 beyond the base of the Eifelian or Lower-Middle Devonian, as they are succeeded 

 by calcareous slates with Calceola sandalina. The succession in the Middle 

 Devonian of North Devon may be paralleled in the Boulonnais, where micaceous 

 sandstones with plant remains are overlaid by marine beds with Strhxaocephahi.-' 

 Imrt'mi. 



The Hangmans Grits are succeeded by the Combe Martin Beds, grits with 

 occasional ferruginous crinoidal limestones, and these bv the Ilfracombe Beds, 

 shales and limestones with crinoids and coral.'!. Except for an alleged occur- 

 rence of Stringocephalus which cannot now be verified , no distinctive forms 



