[ells] PALJ^^OZOIC outliers IN THE OTTAWA RIVER BASIN 139 



sand, supporting at present a growth of small pine. As lor much of 

 \he underlying clay its origin is doubtful. Shells are found only at rare 

 intervals, but in character the sediments strongly resemble the marine 

 clays of the lower Ottawa. Organic remains have, however, been found 

 at widely separated points in the valley, up to elevations of over four 

 hundred and fifty feet above sea level. The overlying deposits of sand 

 and gravel are frequently w^ell stratified, and excellent sections of these, 

 as well as of the underlying clays, are presented along juany of the 

 streams which have cut deep channels in the drift. In these Saxicava 

 and other forms are found. 



While there are no exact determinations as to the altitude of the height 

 of land north of the Ottawa, several close approximations have been 

 obtained l)y means of barometric observations. The elevation of the 

 Iroquois Chute (Labelle). on the Eouge Eiver, has been fixed by the suryey 

 of the railway from St. Jerome at 875 feet on the terrace level one hundred 

 feet above the river, though the elevation of the ridge east of St. Fanstin, 

 which the railway crosses, is 1 ,520 feet. The elevation of the height of land 

 to the northeast 1 letween the head waters of the Eouge and the head of the 

 Mattawin, a branch of the St. Maurice, will not probably exceed three 

 hundred feet more, as we enter upon a broad extent of plain sandy country 

 beyond the bend of the river near the Nominingue Lake and Creek, so 

 that the height of land in this direction would not be far from 1,050 to 

 1,100 feet. Further west, near the sources of the Cxatineau and upper 

 Ottawa, the height of land has been estimated, by Dr. Eell, at about the 

 same figure, the elevation of Grand Lake being put at about 860 feet. 

 From observations by A. E. BarloAv, the height of the Abittibbi divide, 

 north of Lake Temiscaming, is put at 923 feet, while that at the head of 

 Montreal Eiver is not far from 1,800 feet, the elevation of Lake Temis- 

 caming being only 585 feet. Continuing round by the south the height 

 of the divide at Lake Nipissing is only 642 feet, but this gradually rises 

 till, at the head waters of the Muskoka and Petawawa, it is, according to 

 Murray, about 1,400 feet. Near the source of the Madawaska Eiver at 

 Papineau Lake, the same authority gives the elevation at 1,121 feet. 

 Murray also places the source of the Little Madawaska at 860 feet, and 

 of Wahsuhze Lake at the head of the Maganetawan at 1,097. Further 

 east the height of the divide at the head of the Eideau lakes, according 

 to the Canal survey, has sunk to 4l7 feet. 



The principal area of fossiliferous sediments in the Ottawa valle}', is 

 that which extends up the lower part of the Ottawa Eiver from its junc- 

 tion with the St. Lawrence and is continuous with the great area which 

 occupies the valley of the St. Lawrence for hundreds of square miles. 

 Prioiî to the deposition of these sediments a deep depression must have 

 extended northwestward from that river for many miles and the drainage 

 basin of the Ottawa, even at that early time, was well established. The 



