EASTERN FOOT-HILLS. 47 



range. Beyond this sandstone wall, the Colorado group occurs, exhibiting 

 its dark shales and yellow marls. This sandstone wall is cut by the Chug- 

 water, showing a fine section through the entire Dakota beds. Immediately 

 south of the Chugwater, the Dakota beds make an abrupt break, turning 

 to the southwest, and, in a very short distance, are found with an almost 

 due east and west strike. Indeed, all the beds turn in a very abrupt 

 manner, inclined at high angles; the Red Beds standing at 55° to 61°. 

 Where the strata are found with an east and west trend, the dip falls off to 

 25° and 30°. Here the Palseozoic limestones, with a uniform dip of about 

 25°, are found north of the stream. 



The Red Beds, which are well exposed, occupy a very consider- 

 able area, forming a small valley, through which for a short distance 

 runs the Chugwater, the stream having cut for itself a narrow channel in 

 the upper red clays. A section across the Red Beds at this point has 

 already been given. On the south side of the Chugwater occurs a long, 

 low ridge, rising but a few hundred feet above the stream, at the base 

 of which the Jurassic marls and limestones crop out, while the top is 

 formed of the Dakota sandstones, which incline gently toward the plains, 

 and are overlaid unconformably by the Pliocene Tertiary beds. Just 

 west of the wagon-road occurs a somewhat prominent hill, in which is 

 exposed a good section of the Jurassic beds. The base of the hill on the 

 north side consists of the intensely red Triassic rocks, overlaid by the 

 Jurassic marls, which in turn are capped by the Dakota sandstones, form- 

 ing the summit of the hill. Immediately beyond the hill, the entire series 

 of strata again trend to the northward, which, standing at a high angle, are 

 seen compressed into a comparatively short space. They trend at first 

 north and south, then east and west, and again curve around to the north 

 and south, forming approximately three sides of a square scarcely 3 miles 

 in width. The Palaeozoic limestone extends high up on the flanks of the 

 Archaean, while the Triassic and Jurassic rocks have been worn away by 

 erosion, in many places several hundred feet, but the harder and more 

 rigid Dakota beds are seen forming a somewhat prominent ridge. The 

 clays and marls of the Colorado group occupy the centre of the square, 

 but are largely concealed by loose soil and gravel. At the entrance to the 



