west of Richmond and southwest of the Sauk river; also, tracts one to two miles wide along the northeast side of this river; the greater part of the plains of modified drift in St. Joseph, St. Cloud and Maine Prairie; Winnebago prairie on the Mississippi river in southeastern Brockway and northern Le Sauk; and limited areas of the modified drift in St. Augusta, Lynden and Fair Haven. Most portions of the modified drift which are not prairie bear only a scanty growth of timber, in which black and bur oaks are the leading species. Fully half of the county was originally covered by large timber, considerable of which still remains, though much wooded land has been cleared to make farms. Basswood, and species of oak, elm, maple, ash, birch and poplar, are the principal trees. A grove of white pines occurs on the bluff of the Mississippi river in St. Cloud; and both white and jack pines grow on the plain of modified drift that borders this river in Brockway. Tamarack flourishes in swamps, and supplied the name of the Watab river, and thence of Watab township in Benton county, this being the name given by the Chippewas to the long threads obtained by splitting tamarack roots, used by them in sewing their birch canoes.
Geological Structure. Outcrops of Archaean rocks, chiefly syenite, occur in Ashley, Sauk Centre and Melrose in the northwest part of this county; and in Wakefield, Rockville, St. Joseph, St. Augusta, St. Cloud, Le Sauk and Brockway in its eastern half. Cretaceous beds, containing thin seams of lignite, are exposed in the banks of the Sauk river near Richmond in Munson township, and at other localities a few miles from Richmond both to the north and south. Other portions of this co unty, and even the greater part of the county, are covered by the glacial and modified drift, having no exposures of the underlying formations.
Cretaceous Beds. Before the ice age Cretaceous strata probably covered the western two-thirds of Minnesota, and on this area the greater part of the material of the drift is derived from these beds. The remnants of them that escaped the glacial erosion are now nearly everywhere concealed by the drift. In Stearns county their only exposures are found in the neighborhood of Richmond.
Mr. Eames observed the following section, horizontally stratified, near this village, in the banks of the Sauk river: Sand and gravel (modified drift), 40 feet; blue clay with crystals of selenite, 4 feet; impure coal (lignitic clay, including three inches of lignite), 2½ feet; bituminous limestone, forming the bed of the river, 10 feet.
This was doubtless at the locality of the drift and shafts mentioned beyond; and the report of limestone in place is an error. About half a mile below this exposure, Eames reports a ferruginous sandstone or conglomerate four feet thick, seen in the bank of the river along a distance of twelve yards.
Three miles north of Richmond, in the S. E. ¼ of the N. E. ¼ of section 2, Munson, north of the range of morainie hills, a section noted by Eames in a ditch dug for drainage consisted of yellow and blue clay with three seams of lignite from one to six inches thick. The stratification here was irregularly confused and in part vertical, apparently on account of slides. Three
