1852.] BIGSBY GEOLOGY OF THE LAKE OF THE WOODS. 405 



In no part of the Lake of the Woods were any traces of metallic 

 ores discovered, although carefully looked for. 



We have yet to notice the limestone of the Lake of the Woods. 

 It was not seen by me in juxtaposition with the crystalline rocks 

 just described, but in mere shreds of strata, some miles off, in a low 

 country, and buried beneath mounds of quartzose sand, clay, and 

 immense assemblages of blocks from the north, — a country first de- 

 nuded and then filled up with foreign debris*. 



The limestone, whether fixed or loose, is only found on the south 

 and west shores of Sandhill Lake. Near the south side of Driftwood 

 Point, a little to the south side of Reed River, and at a third spot 

 within the mouth of Rainy River, where dry banks replace the rushy 

 swamp of the lake, there are (half buried in gravel) square, sharp- 

 edged angular slabs and blocks of deep straw-yellow limestone, of a 

 fine close grain. 



Each of these fixed masses is from 1 to 15 feet broad, and 3 feet 

 deep. They are all cracked and fissured by the intense cold of the 

 climate. For several miles around these points, as well as elsewhere, 

 the beaches are strewn with loose, flat, shingly fragments of lime- 

 stone, which are largest and most numerous in the immediate vicinity 

 of these points. They seem to have resulted from the action of the 

 weather, ice, and waves. Together with these fragments occur 

 travelled blocks of crystalline rocks. 



I saw this same yellow limestone strewn plentifully over the west 

 arm of Rainy River Bay, and on the shores of Elm Island. 



On the right bank of Rainy River, not far from its mouth, are the 

 fixed remains of an unfossiliferous calcareous breccia, consisting of 

 yellow fragments in a brick-red paste. 



My reasons for thinking these patches of limestone to be fixed, 

 are — first, their position and aspect; secondly, the peculiar form 

 of the coast on which they are found, which is usually indicative of 

 the presence of sedimentary rocks ; and thirdly, my being aware that 

 on the west limestone shows itself as soon as the elevation of the 

 ground will permit. The abundant, well-preserved, and often large 

 fossils of this Umestone (principally casts) show that it belongs to 

 the Upper Silurian age ; but to which particular division Mr. Salter, 

 of the Museum of Practical Geology, who has kindly examined them, 

 says that it is at present impossible to determine. The condition of 

 the fossils shows that the animals must have died in situ. 



My time having been always limited, I was only able to collect 

 specimens of the following organic remains : — a very small and elegant 

 Phacops ; small Orthocerata, with wide chambers ; minute Encrini- 

 tal columns ; various Corals, especially the Favosites Gothlandica and 

 Cyathophyllum ; Murchisonia, Pentamerus Knightii, Leptcena, Avi- 

 cula, Ati'ypa, and Spirifer. 



The following is a general view of the outlines of this calcareous 

 basin. 



* See Dr. Bigsby on the Drift of the Lake of the Woods and South Hudson's 

 Bay, Quart. Journ. Geol. Soc. vol. vii. p. 215 et seq., and Map, PI. XIV. 



