tfALcorr.J MAINE. 69 



The resemblance of these rocks to the Acadian slates of the Boston Basin and St. 

 John is very marked; and I join with Prof. Hitchcock in anticipating the discovery 

 on the Maine coast of characteristic Primordial fossils. 1 



Iii describing a geologic map of Maine, Prof. Hitchcock says that he 

 is unable to divide the Cambrian and Huronian, owing to a want of 

 knowledge of their distribution. 



They are the* talcose and mica schists of the reports, called the Quebec group by 

 H. Y. Hind and Sir W. E. Logan; the St. John's group in New Brunswick, and the 

 Merrimack, Rockingham, Kearsage, Andalusite, and Coos groups of the New Hamp- 

 shire reports. * * * They were called Cambrian in New Brunswick by Gosner, 

 and in our second report it was said that this term might ultimately express their 

 true age. Subsequently Bailey and Matthew referred them to the Lower Devonian 

 but the drift of opinion is towards the earlier view at present. 2 



On the map it is very difficult to make out the distribution, owing to 

 the color of the Laurentian, Silurian, and the Cambrian being appa- 

 rently identical. The supposed Cambrian rocks of New Hampshire 

 and southeastern Canada follow up the valley of the St. John River 

 from a little distance above the entrance of the Allegosh River, and 

 along the Canadian boundary line nearly to the boundary of New 

 Hampshire. The Canadian extension of these rocks is described more 

 in detail and will be mentioned under the head of the Canadian Exten- 

 sion of the Northern Appalachian District (Chapter iv). 



In the latest contribution that we have upon the subject of the geo- 

 logical age of the siliceous slate and associated sandstones or quartz 

 rocks of Mount Desert, Maine, Prof. Shaler says: 3 



We note in the first place that there is a total absence of limestones in all the sec- 

 tions exposed to view. A careful study of the drift materials on the south part of 

 Mount Desert and on the Cranberry Islands where we could hope to find traces of 

 hidden limestones shows that there are no limy beds in the sodimeutary deposits of 

 this island. The aggregate thickness of the various Mount Desert sections can not be 

 less than about 6,000 feet and may amount to one-half more than this estimate. It 

 seems as if this fact must exclude the hypothesis that these strata were formed any- 

 where in the periods above the level of the Cambrian, for nowhere above that level 

 do we have any such sections barren of limy matter. 



It may be next noted respecting the schistose series of Mount Desert that those of 

 its east and west margins are of singularly uniform composition. They were doubt- 

 less origiually shales and thin sandstones of great uniformity of structure. Their 

 texture is not such as at all points to exclude the preservation of fossils; iudeed the 

 greater portion of the deposits are well fitted to exhibit organic remains, yet they 

 have afforded no trace of them. Nowhere above the level of the Cambrian series do 

 we find any section of this description. On these grounds, it seems reasonable to 

 place the greater part of the Mount Desert rocks in the lower portion of the Cambrian 

 section, if not yet lower iu the geological column. 



This coincides with the views of Hitchcock and Crosby, that the 

 strata under consideration are of pre-Silurian and probably of Cambrian 

 age. 



'Op.cit.,p. 117. 



'Geological map of Maine (with noted on geology of)- In Geology of Northern New England, 

 1885, p. 2. 



3 The geology of the island of Mount Desert, Maine. Eighth Ann. Rep. U. S. Geol. Survoy, pt. 2, 188ft 

 p. 1059. 



