90 NORTH AMERICAN FAUNA. [no. 27. 



Near this point the tar sands begin to show beneath the Clear- 

 water shale, and for the remainder of the way to below the Clearwater 

 form a conspicuous element of the banks. Two miles below the 

 Boiler, Middle Rapid, similar to the last, and 5 miles lower down, the 

 Long Rapid, both usually run on the right side, occur. At the 

 Crooked Rapid, 6 miles below, the river makes a sharp bend to the 

 right. This rapid is run on either side. The river is here bordered 

 on the right side by a band of Devonian limestone, about 15 feet in 

 thickness and highly fossiliferous. The remainder of the bank is 

 mainly composed of the tar sands. Near this point a low anticline 

 occurs, and the strata begin to dip slightly toward the north. As this 

 dip is about equal to the fall of the river, the character of the banks 

 varies but little for many miles. 



All along the river between Athabaska Landing and the mouth 

 of the Clearwater, and especially among the rapids, much of the 

 country is partially or wholly denuded of timber, the result of suc- 

 cessive forest fires (see fig. 2, p. 18). This circumstance is largely 

 responsible for the numerous landslips. In the spring these dead- 

 enings with their immense stretches of fallen timber are very un- 

 sightly, but in early fall these same areas are solid masses of color 

 from the purple flowers of the fireweed {Ohamcenerion.) 



Two miles below Crooked Rapid occurs Rock or Stony Rapid. 

 Here large boats are usually run oh the left side, but canoes toward 

 the right bank. Five miles below, the Little and Big Cascades occur 

 within a mile. These are caused by ledges of limestone which cross 

 the river somewhat diagonally. The Little Cascade is run by large 

 boats close to the right bank, and the Big Cascade toward the mid- 

 dle of the river, but in both cases canoes keep close to the left bank. 

 These rapids cause much trouble at times of low water. About 7 

 miles below the Big Cascade another limestone ledge obstructs naviga- 

 tion, forming the Mountain Rapid. This contains heavy swells, but 

 may be run by lightly loaded canoes. The rapid is usually entered 

 near the left bank. A stretch of comparatively quiet water near the 

 middle of the rapid affords an opportunity to cross to near the right 

 bank, where the water is smoother. Six miles below a slight rapid, 

 called the Moberly, is passed, and 3 miles beyond. Fort McMurray, 

 at the mouth of the Clearwater, is reached. (See PI. IV, fig. 2.) 



Fort McMurray is a former post of the Hudson's Bay Company, 

 situated on the right bank of the Athabaska a short distance above 



°A trading post was established at this point in 1S70, and for some years 

 was known simply as 'The Forks,' but was later named Fort McMurray. It 

 was removed in ISP!) to the mouth of Little Red Hirer and named Fort 

 MacKay. The name Foil McMurray is still used to indicate the original site, 

 but it is now occupied mainly by private traders and more or loss irregularly 

 by the Hudson's Bay Company. Here the Orahame receives its northward- 

 bound cargo from the scows. 



