90 GEOLOGICAL SUKVEY OF THE TEREITOEIES. 



On the northwest side there is a low ridge, the summit of which is 

 composed of Upper Cretaceous rocks. The valley as well as the high 

 ground is covered with the drift material. The evidence seems to be 

 clear that much of this drift deposit is local and derived from the mount- 

 ains in the immediate vicinity. 



All along the base of the mountains, interrupted occasionally^ is a 

 deep valley varying from three to ten miles wide, which seems to have 

 been scooped out as it were by forces which must have come from the 

 mountain-ranges. 



At right angles to this valley, and extending down into the plain, are 

 numerous other valleys of erosion, walled on each side by high narrow 

 ridges. Upon the sides of the ridges facing the mountains are the 

 heaviest deposits of drift, extending to the summits of the hills, while 

 the opposite sides are smooth and usually covered with grass. 



Sometimes these hills have quite gentle slopes, facing the mountain- 

 sides, and are so thickly covered with loose rocks that no vegetation 

 can gain a foot-hold, while the opposite sides descend abruptly and are 

 clothed with vegetation, with scarcely a pebble on the surface. 



Whether all the drift phenomena of this region are due to these local 

 influences I will not now attempt to decide, but we believe that the 

 greater portion of them may be accounted for from the joint action of 

 water and ice operating from the direction of the mountain-ranges in 

 the immediate vicinity. In my final report I shall attempt to discuss 

 these points more in detail. 



Westward from Cooper's Creek, eleven miles, we come to the deep, 

 wooded, and somewhat fertile valley of Eock Creek. 



Soon after leaving Cooper's Creek west we observe the Tertiary rocks 

 beginning to overlap, and six miles distant we come to a most excellent 

 exposure of the coal beds. The slopes are all so gentle, and the super- 

 ficial drift deposits cover the surface to such an extent, that I found it 

 difficult to secure a connected section of the beds in their order of super- 

 position. 



The rusty arenaceous marls of No. 5 seem to pass gradually up into 

 the coal-bearing layers without any perceptible break and without a 

 very marked change in the sediments. The lower beds of the Tertiary, 

 as seen here, are composed of a fine brown grit, very loose, but filled 

 with irregular hard masses of rocks, sometimes in layers extending for 

 a short distance, but usually in the form of concretions. These concre- 

 tions have concentric coats, or they are composed of thin laminoe which 

 separate very readily. 



Underneath the coal there is a bed of drab clay varying in thickness 

 from three to five feet. When the coal is exposed to the atmosphere or 

 the waters are permitted to permeate the overlying strata it has a rusty,, 

 dull-brown appearance, but on penetrating the earth it soon reveals its 

 bright color and compact structure. Above the coal there is another 

 bed of drab, indurated clay, and then over this a loose grit with layers 

 of hard sandstone. 



The clay bed above the coal is full of nodules of iron, also rusty sandy 

 concretions. The dip is above 10° to the northeast from the mountains. 

 About a mile west of the opening described above there is another out- 

 cropping of coal which has been wrought to some extent. This bed is 

 divided by about two and a half feet of drab arenaceous clay. The upper 

 portion measures about five feet, the lower six to eight feet, so that we 

 have ten to twelve feet of solid coal ; some portions look like dull bitu- 

 minous coal, others resembling anthracite very much in appearance. 

 Over the coal is the usual drab, indurated clay, filled with vegetable 



