PLATE LII. 



WADENA AND TODD COUNTIES, 1888. WARREN UPHAM. 



There are two points in Todd county, in the valley of the Long Prairie river, at 

 which the crystalline rocks appear at the surface. One is in Ward township and the 

 other in Villard. But in Wadena county the underlying rock never appears above 

 the drift surface. The outcrop in Villard is a form of gabbro that has somewhat the 

 appearance of dioryte, as well as its composition. This alteration is due apparently 

 to dynamic action in part, since augite is found preserved (No. 1685A), and since the 

 rock at the lumber dam (No. 1687) has the vertical attitude and structure of coarse 

 slates as if at a contact plane where friction and pressure had been powerful. Where 

 this rock is greatly saussuritized it is nearly white (as at the old quarry), the whole 

 consisting very largely of zoisite. This rock may belong to the Archean, but it resem- 

 bles some phases of the gabbro of the Taconic. 



The rock in Ward is quite different and undoubtedly belongs to the Archean. 

 It forms a ridge about eight feet high, twenty rods long, extending northwest and 

 northeast, with a width of three or four rods. It is a light-colored, greenish and 

 grayish syenyte, the light-green color being due to epidote. It is not schistose, but 

 is intersected by joints, and could be quarried to advantage for building stone for 

 the neighborhood. 



Wadena county is wholly covered by modified drift in the form of a plain, which 

 undulates but little from a flat. 



Todd county is divided between till and modified drift, the greater portion being 

 modified djrift. The central portion of Todd county is covered by smooth or undu- 

 lating till, but rhe main streams are accompanied by narrow belts of gravel and sand. 

 Till is found largely in the moraines in southern and eastern Todd county. This 

 till is probably 100 to 150 feet thick and came largely from the northwest, judging 

 from the abundance of limestone in the gravel. Boulders of limestone are not 

 common on the surface except in the southwestern part of the county, where they 

 constitute from one-tenth to one-twentieth part of the superficial boulders. The last 

 movement of drift seems to have been from the northeast. 



The forms and distribution of the moraines, as well as their composition, in 

 in Todd county, will not warrant, with the study that has been given to them, posi- 

 tive statements as to the changes of the glacier during the Glacial epoch. N. H. w. 



