REVIEWS — GEOLOGICAL SURVEY OF CANADA. 325 



compact feldspar. The principal economic minerals of these rocks, 

 comprise crystalline limestone, specular iron ore, magnetic iron ore, 

 workable slates, and quartzites : the white varieties of the latter being 

 apparently available for glass-making purposes. At Iron Island, on 

 Lake Nipissing, the specular iron ore appears in force. " Small masses 

 are common to most of the rock in the island, and in the crystalline 

 limestone there is a very great display of it. For a breadth of about 

 forty yards along the cliflF on the east side, the rock holds masses of 

 the ore of various sizes, sometimes running in strings of an inch thick 

 or upwards, and at other times accumulating in huge lumps, some of 

 which probably weigh over half-a-ton. The beach near the outcrop 

 is strewed with masses of all sizes, from great boulders weighing 

 several hundred pounds, to small rounded pebbles not bigger than 

 marbles. The limestone with which the iron ore is associated, is fre- 

 quently quite cavernous, and the crevices and smaller fissures are 

 thickly lined with crystals of blue fluor-spar and red sulphate of 

 baryta." The following is Mr. Murray's interesting sketch of the 

 general features of Lake Nipissing : 



Above the Chaudi^re Falls, the lower portion of Lake Nipissing takes a general 

 bearing north-east, with an average breadth of from one to two miles, till it 

 expands to the east and west, at the distance of about eight miles into the main 

 body. The west side of this southern arm is deeply indented by a succession 

 of long narrow bays, lying for the most part nearly east and west, and crowds 

 of islands are scattered along the channels and off the shores. From the most 

 southern of these bays, which falls back to the westward for upwards of seven miles, 

 there are two outlets in addition to the one at the Chaudiere, the waters of which 

 appear to unite in their course to the southward, and flow in a single stream into 

 the French River, above the Rapide du Pin, falling in a fine cascade of about 

 twenty feet, close to the junction. 



The southern shore of the main body of the Lake trends in general very nearly 

 due east and west, forming in the last twenty miles of the west end, the south side 

 of a great western arm, which alternately contracts into narrow straits, in some 

 cases only a few chains wide, and opens again into wide expanses, generally crowd- 

 ed with islands. Measuring from the north-east end of the southern arm to the 

 extreme end of the great western bay, the distance is somewhat over thirty-two 

 miles, and from the extreme east end of the lake to the same place, the total length 

 is a little over fifty-three miles, the western extremity reaching longitude by ac- 

 count SC 30' 54" W. This great western bay was called Bear Bay, and between 

 it and the north-west arm, where the survey terminated in 1854, there are two 

 other large westerly bays, divided by a bold rocky promontory jutting out nearly 

 due east, with a multitude of islands in continuation of the strike, stretching far 

 into the lake. In addition to these main features the whole coast is deeply indent- 

 ed by a succession of marshy bays and coves, separated by bold rocky points, and 

 a number of small streams add their tribute to the waters of the lake. 



