No. I.] 



GEOGNOSTICAL OBSERVATIONS. 



509 



slate forms a small island. The primitive strata which we fell in with here, 

 and traced to Isle-a-la-Crosse Lake, seem to be a continuation of the range 

 we quitted at the south end of Play-Green Lake ; and neither at that place nor 

 here could we discover any rocks interposed between them and the limestone. 

 About a mile distant from the above-mentioned island of hornblende slate, cliffs 

 of limestone bound the lake. We had no opportunity of observing the limestone 

 more nearly in contact with other rocks than at this place. The bounding line 

 between the two formations seems to run about W. b. N. from Play-Green Lake 

 to the upper part of Isle-a-la-Crosse Lake. We crossed this boundary line on 

 entering the Ridge River. 



At the Ridge Portage, two miles from the mouth of the river, a ridge of 

 mica slate crosses the stream. Its strata dip N.E. at an angle of 45°. From 

 this place up to the junction of Hay River, the mica slate in irregular ridges 

 bounds the stream. Above Hay River, sixteen miles from Beaver Lake, 

 the river is wider and less rapid, and is termed by the Canadian voyagers, 

 La grande rivi&re. Here the mica slate is succeeded by gneiss, which 

 forms irregular roundish eminences, rising a hundred and fifty feet above 

 the water. The gneiss is traversed in every direction by veins of flesh-colour- 

 ed felspar, and contains many kidneys of mica slate. These rocks are very 

 sparingly covered with soil, and consequently support few trees. At the Carp 

 Portage *, fifteen miles N.W.b.N. of the Ridge Portage, there occurs a light 

 red-coloured rock, composed of felspar intermixed with hornblende, together 

 with a small quantity of quartz of the same colour with the felspar, and having 

 disseminated a few grains of iron pyrites. This rock is intersected by veins 

 of felspar, and contains kidneys of mica slate. 



At the Birch Discharge, six miles N.N.W. of the Carp Portage, the same 

 rock alternates with mica slate. The boundaries of the stream between 

 these portages consist of the rounded ridges of gneiss above-mentioned. At 

 the Birch-point Portage, two miles and-a-half above the Birch Discharge, the 

 strata, consisting of grey gneiss, dip to the N.N.E. at an angle of 30°. The 

 gneiss rocks continue with little variation for eleven miles, as far as Island Port- 

 age, where the rock running across the river, and producing a fine cascade, may 

 be termed thick mica slate, containing much quartz. The strata dip here to the 



* So named from the great number of sucking Carp (Catas tomus Hudsonius), which are ob- 

 served endeavouring to surmount the rapid in the spawning season. 



