SECTION OF BIRDS HILL. 185 



north, these eskers ag-aiu rise in plateans, ridges, and hills in sections 19 to 

 22, townshij) 12, range 5 east, cnlniinating in Griffiths Hill, in the northeast 

 quarter of section 19, about 875 feet above the sea, or a little more than 

 100 feet above the railway, 2 miles distant on the west. This whole group 

 of elevations is composed of gravel and sanil, irregularly bedded, which 

 appear to be deposits formed near the mouths of glacial rivers where they 

 flowed between walls of ice, and were here and there divided by ice islands, 

 whose melting left these hills, ridg-es, and plateaus bounded bv moderately 

 steep slopes and separated by intervening depressions. Witli the comple- 

 tion of the melting- of the ice about and beneath these de2)osits they sank 

 to the bottom of Lake Agassiz, here aljout 500 feet deep; and the infre- 

 quent bowlders tliat are found scattered upon their surface were dropped 

 from floating ice. Toward the north, west, and southwest they are 

 bounded by the flat plain of tlie Red River Valley, 750 to 760 feet above 



^50t^^ ^. d , o -a.^-^" coMse- c»Av£L Afvos.Afio '£s>r£/^, ■ ^.-^-'^—^ — '^'^^i' a^^yg-L'^/vo sAyvo;^:p::r~7^ \*i c 



Fig. 10.— Section uf Birds Ilill. Horizoutal scale, oue-fourtb milu to an inch. 



the sea, while toward the east and southeast they are connected with 

 plains and undulating tra(;ts of gravel and sand ^\'hich reach with slow 

 and gradual ascent to the Lake of the Woods and mto Minnesota. 



An instructive section of Birds Hill (flg. 10) has been made in the 

 excavation of its gravel and sand for railway ballast. This massive esker 

 extends from the railway station about 1 mile east-southeast and thence a 

 half mile southeast, beyond which it is coimected by a low ridge with the 

 jjlateau of sections 35 and 3G, township 11, range 4 east. Its width is a 

 quarter to a half of a mile; and its maximum height, one-thii'd to two-thirds 

 of a mile from the station, is 45 to 50 feet above the railway and the flat 

 plain that extends thence west. The elevation of Birds Hill station is 759 

 feet, and of the crest of this hill 805 to 810 feet, above the sea. It has a 

 broadly rounded top, with gentle slopes on all sides. Along its northern 

 slope an excavation reaches three-fourths of a mile, varying in width from 



