

B. N. A. BOUNDARY COMMISSION, 
Re made analyses of two samples, 40-5 and 17'8 per cent. respectiv sly ¢ 
magnesic ala ** Wi 





eye and Shier divisions of the Lower Silurian, and the operatibagll of 
Canadian Geological BUrrey lately extended to ous negiOn, will no do 



ment is as follows in descending order: + 


Hudson R. Maquoketa Shales. 
Galena Limestone,—(buff and blueish magnesian limestone,) 
: Trenton Limestone,—(flaggy limestone, with shale, ) : 
mr’ Chazy. St. Peter Sandstone ,—(white and friable pure quartz sand,) 125 > ae 
iS Galcttcrons. Lower Magnesian Limestone,—(light buff, some beds sand, )about 200° 
St. Croix Sandstone, —(massive white or buff coloured, shale at 

Trenton. 



















base,,) over 500°") i a er 
a oF Potsdam. Potsdam Sandstone,—(hard sandstones, often red,) at haat 400 i oe 
a | 22, Fragments, known by their mineralogical character and the 
fossils which they contain, to have belonged to these Silurian limestones 
of the first prairie level, have been strewn broadcast’ over the plains 
wr « 
- 
a. almost to the Rocky Mountains, by glacial agency during the period 
* of the drift. . 
ee 23. They also, without doubt, underlie the greater part of the intaeioee 
- continental area, though completely covered by rocks of later date ; and 
; they are known to occur again in some parts of the Rocky Mountains 
ae but considerably modified in appearance and thickness. Their eastern. . 
line of outcrop follows the Laurentian, to the north, occupying a broad _ — 
belt of country to the head waters of the Mackenzie, where they appear 
to be overlapped by Devonian strata. Other smaller areas of Silurian, | 
however, appear further north along the same line of strike, and lime- 
stones probably referable to this age, again expand widely on the shore bh 
of the Arctic Ocean. , 
eee 24, Limestones very similar in appearance to those of Silurian age, 
but known to be Devonian by their included fossils, occur on Manitoba 
and St. Martin’s Lakes, and elsewhere along the western border of the 
the northern part of the first prairie level. Prof. Hind has defined by 
observations in several localities a belt of these rocks at least fifty miles 
in width. He describes them as in intimate connection with the brine — 
springs of that district, the waters of which yield an excellent quality of — 
salt on concentration. From the continuation of such saline springs to 
La 
. ie 



‘ ’ — 
* Dr. D. D, Owen’s Report. + See Prof. N. H, Winchell’s Reports, &e, 

