354 THE GLACIAL LAKE AGASSIZ. 



for tlie next 75 miles to the north-nortliwest is the conspicuous escarpment 

 called Pembina Mountain. 



The north end of this massive beach bears on its crest an artificia 

 embankment 100 feet long from east to west and 20 feet wide, raised 2 feet 

 above the natural surface, its toj) being 1,225 feet above the sea. This is 

 10 rods south from where the beach is cut to 1,210 feet by a wide gap, as 

 of some ancient watercourse. In the south edge of the southwest quar- 

 ter of section 17, Gardar, on the south bank of the North Branch of Park 

 River, about 10 rods east from the ford of the "Half-breed road," this beach 

 has an elevation of 1,220 feet. 



North Branch of Park River at this ford, 10 to 15 feet wide and a few 

 inches deep, 1,203 feet. Surface at the village of Gardar, a mile east, 

 1,175 to 1,170 feet. Lower Herman beach, passing from south to north 

 along the east side of sections 20 and 17, Gardar, a thud of a mile west of 

 the village, about 1,185 feet. 



FROM GARDAR NORTH TO THE TONGUE RIVER. 



(PLATE XXX.) 



Sections 17, 8, and 5, Gardar, rise from 1,190 and 1,200 feet on their 

 east side to 1,220 and 1,225 feet on the west, including, therefore, the 

 upper Herman shore of Lake Agassiz; but they present no considerable 

 deposits of beach gravel and sand. A swell of till, sprinkled with very 

 abundant bowlders, nearly all Archeau granite and gneiss, up to 5 feet in 

 diameter, extends from south to north across the line between sections 8 

 and 5, having its crest at 1,215 feet, from which there is a steep descent of 

 10 or 12 feet to the west. Sloughs and pools of water, permanent through 

 the year, lie in the west part of section 5, about 1,190 feet above the sea. 



The South Branch of Cart Creek, in sections 31 and 32, Thingvalla, 

 is bordered by a belt of timber a half mile wide, but it has only a small 

 channel a few feet below the general surface, and is dry through the greater 

 part of the year. Its alluvial gravel, like that of the Middle and North 

 branches of Park River, is mostly Cretaceous shale, derived from the 

 gorges eroded in this rock at the sources of these streams in the Pembina 

 Mountain. 



