12 ASSINNIBOINE AND SASKATCHEWAN EXPEDITION. 



a swamp or marsh, fringed with small spruce and tamarac 

 in the rear. I aroused the men at 4 a.m. The aurora at 

 that hour was a splendid object, and appeared in the form 

 of sudden flashes of low arcs of light, complete from east 

 to west, rising in vast waves from one constant luminous 

 base, a few degrees above the horizon. The undulations 

 of pale light followed one another with great rapidity and 

 regularity for many minutes together. 



A strong westerly breeze early this morning, soon 

 enabled us to reach the Sandy Bar, fourteen miles from 

 Drunken Eiver, and then the Grassy Narrows, a distance 

 of seven miles. Both of these points are low, sandy, and 

 gravelly peninsulas stretching out into the lake opposite 

 to Big Black Island. The first exposure of limestone was 

 seen on a small island opposite Big Black Island, which 

 we named Guano Island. It dipped very slightly to the 

 south-west ; a search for fossils was fruitless, but on Big 

 Black Island, and those adjacent to it, near the Little 

 Grindstone Point, limestone of Lower Silurian age ap- 

 pears in the form of low mural cliffs on the west shores, 

 which alone were seen. This limestone is a continuation 

 of a fine exposure afterwards found on Deer Island, 

 where we arrived at 1 p.m. 



The following section occurs on Deer Island : — 



Shingle Beach (Limestone) : 



No. 1. Four feet of dark green argillo-arenaceous shale, 

 with thin layers of sandstone of uneven thickness — 

 Eucoids very abundant in the sandstone. The weathered 

 sandstone is reddish brown ; fresh surfaces are white or 

 grey. White iron pyrites assimilating the forms of disks, 

 spheroids, and shells occurs in the sandstone. 



No. 2. In many respects like the former ; the sandstone 

 layers are from one to four inches in thickness and pre- 



