1858.] DAWSON LOWEE COAL-MEASURES. 63 



I. Characters and extent of the Lower Carboniferous Rocks. 



The occurrence of beds containing coal-plants in connexion with 

 the Lower Carboniferous marine deposits of ISTova Scotia was ob- 

 served by Sir W. E. Logan in 1841, though at that time the true place 

 of the beds was not understood, owing to the belief that the lime- 

 stones afterwards ascertained to be Lower Carboniferous were of Perm- 

 ian date. Sir C. LyeU examined these beds in 1842, as they occur 

 at Horton Bluff ; and the author subsequently more fully examined 

 their relations to the marine limestones, and traced them in various 

 parts of Nova Scotia, and at the Albert Mine in New Brunswick*. 



This series may, in general terms, be characterized as consisting 

 of shales and sandstones destitute of marine shells, and containing 

 fossil plants, fishes, and entomostracans, locaUy underlying the great 

 marine limestones and gypsums of the Lower Carboniferous series, 

 and separated by these from the true coal-measui^es, from which 

 they are also in some respects distinguished by mineral character 

 and fossil remains. I have said locally underlying the marine lime- 

 stones, because I believe that in some places they are strictly con- 

 temporaneous with these, forming estuary-, lagoon-, and swamp- 

 deposits at their margins. 



To avoid repetition of details previously given, I have thrown 

 into a tabular form the structure of this part of the Carboniferous 

 system, as it appears in some of the best exposures. I have in this 

 table slightly modified the names proposed in former papers for the 

 subdivisions of the system, calling the true productive coal-mea- 

 sures the middle, instead of the lower series, and transferring the 

 latter term to the beds described in this paper, formerly described as 

 pseudo-coal-measures underlying the carboniferous limestones. 



The first and second columns in the annexed Table represent the 

 structure of this formation in the western part of Nova Scotia, where 

 the true coal-measures and upper coal-measures are scarcely, if at 

 all, developed, and where the lower carboniferous marine deposits 

 attain their greatest thickness. I had an opportunity in June last 

 of re-examining the best sections of this part of the province, in 

 company with Dr. Harding and Professor How, of Windsor, and the 

 Pev. ISIr. Band, of Hantsport. At Horton Bluff, several faults 

 oppose some difficulties to an accurate measurement of the thickness ; 

 but I have estimated these strata at 600 feet in all, apparently de- 

 stitute of true marine remains, and marked HthologicaUy by a great 

 proportion of dark and grey sandstones and shales. Prom the 

 localities mentioned in the Table, these beds may be traced along the 

 margin of the metamorphic country as far as the Shubenacadie 

 River, and probably as far as the valley of the Stei\T.ocke, fifty miles 

 distant from Horton. They reappear along an anticlinal line par- 

 allel to the former, at Walton, Noel, and other places on the coast 

 of the Bay of Fundyf. The intervening trough is filled with the 

 marine limestones and the accompanying marls, red sandstones, 



* Quart. Journ. Geol. Soc. vol. i. p. 31 ; iv. p. 59 ; v. p. 335 ; vii. p. 398 ; 

 ix. p. 107. t Quart. Journ. G-eol. Soc. vol. vii. p. 389. 



