HOUSTON COUNTY. 



229 



Alluvial terraces. | 



feet above the flood plain. The track of the railroad is about one foot above the flood plain of 

 the river, which is eighteen feet higher than the water below the mill-dam. 



At Money Creek the terrace rises thirty feet above the flood plain, which is twenty feet above 

 low water below the mill-dam. The contents of the terrace are stratified. On sec. 30 in this town 

 the contents of the Root river terrace and their arrangement, are shown by the following sketch, 

 which was taken on the spot. 



FIG. 6. SECTION OF THE ALLUVIAL TERRACE, SEC. 30, MONEY CREEK. 



Explanation. 



a. Mixed and broken stratification, roots, soil, &c., 24 ft. A. Strata of fine sand or clay. 

 6. Loam and sandy loam. 3 *> feet. t. Sloping clay layers, damp, rusty. 



c. Oblia ue strata of light sand. j. Dry, blowing sand. 



d. Loam and light sand k. Wet clay with rusty lumps. 



e. One layer of sand blown out. Sin. I. Contorted, curling, or massive strata. 

 /. Oblique layers of sand. x. Hid from veiw by debris. 



g. Horizontal strata of fine sand. 



The full hight of the bank is about twenty feet where the section is taken. At a point far- 

 ther to the right than is shown in the sketch a couple of bones were found, but in the confused 

 and broken uppermost layer. They were where that layer comes down to the river, and about 

 three feet below the surface, or five feet above the water of the dam, the surface of the bank 

 sloping about forty-five degrees. 



At Hokah the village is on a terrace sixty-five feet above the flood plain of Root river, and 

 there is a distribution of loam about the bluffs at a higher level (as well as at many other points 

 along Root river valley), reaching to a hundred feet, or a little more, above the flood plain. This 

 loam appears in indistinct benches or terrace levels, or patches of terrace, rising often with a slope, 

 far up the rock-bluffs. It very rarely appears level, as a well-marked terrace. It suggests rather 

 a worn-out old terrace level, the upper surface of which has suffered erosion, by being gullied out 

 and smoothed off toward the river. It is generally cultivated for farms, and has good wheat-fields ; 

 consisting of the same materials as the lower terrace. Its actual hight is difficult to ascertain. 



S. W. \ sec. 22, La Crescent. By the road-side appears a terrace rising about fifty feet, 

 which at the top consists of the fine loam of which the foregoing terrace is composed, showing at 

 least eight feet of such material, while its lower twenty feet are of drift-gravel which is coarse and 

 obliquely stratified, the coarsest pebbles being but one or two inches in diameter. This occurs on 

 the rounded point of the rock-bluff which faces both valleys. 



The village of La Crescent stands on a beautiful terrace of drift gravel, generously laid out, 

 with wide streets and alleys, fifty feet above the flood-plain of the Mississippi. This terrace slopes 

 gradually back toward the high rock-bluffs. It is surmounted, along the bluffs, by another terrace 

 rising forty feet higher, which consists of loam. 



This drift gravel must be attributed to the agency of the river. It has every feature of a 

 water-worn alluvial deposit. It is not found in Houston county in any of the valleys of other 

 streams, back from the Mississippi. It antedates the loess loam, as that is terraced above it, and 

 probably bears the same relation to an earlier glacial epoch, as the terraced loam does to the last. 



At Brownsville the loam terrace is eighty feet above the flood-plain of the Mississippi. 



