HOUSTON COUNTY. 213 



Soil and timber.] 



The folloiving measurements by aneroid barometer will show the depth 

 of some of the valleys below the immediate upland at the points named. 



Section 17, Caledonia, three miles south of Sheldon. Beaver creek, at the great spring, is 

 230 feet below the tops of the bluffs ; which embrace the Shakopee limestone, Jordan sandstone 

 and a part of St. Lawrence limestone. 



At Sheldon the bluffs are 420 feet high. 



At Houston the bluffs north of the city are 520 feet above the level of water in Root river in 

 summer. 



At Hokah Mt. Tom rises 530 feet above the flood-plain of Boot river. 



On section 11, Union, the ridge between Thompson creek and the railroad, at the sculptured 

 rock, rises 355 feet above the highway directly south of the ridge. 



At Brownsville the hight of the bluff above the flood-plain of the Mississippi is 495 feet 

 Mr. Fred. Gluck, of Brownsville, measured the same by triangulation in the winter season, and 

 obtained 486 feet as the hight above the ice. Railroad surveyors are said to have obt dned 483 

 feet as the hight of the same bluff. The most of this hight is made up of sandstone, there being 

 but 105 feet of limestone in the upper part of the bluff, belonging to the St. Lawrence formation. 



Mean elevation of the count;/. From the contour-lines shown on the county 

 map the average elevation of each township above the sea may be estimated, 

 with the following result: 



La Crescent, 900 feet above the sea; Hokah, 875; Brownsville, 1000; 

 Crooked Creek, 900; Jefferson, 850; Mound Prairie, 950; Union, 1025; May- 

 ville, 1075; Winnebago, 1050; Houston, 925; Sheldon, 975; Caledonia, 1125; 

 Wilmington, 1175; Money Creek, 950; Yucatan, 1000; Black Hammer, 1025, 

 and Spring Grove, 1175. The mean elevation of the county, derived from 

 these figures, is approximately 990 feet above the sea. 



The soil and timber of Houston county. The soil of the county is formed 

 by the loess-loam. It is very fertile, and apparently very enduring. It is 

 mainly a clayey deposit, without stones or gravel, but yet in some places 

 becomes arenaceous, the sand grains being very fine. The loess is hardly 

 pervious to water. In the scarcity and costliness of common wells, many 

 farmers resort to the expedient of retaining the surface water, after rains, 

 in open reservoirs produced by throwing a low dam across some of the 

 shallow drainage valleys that intersect their farms, thus forming with the 

 common loam a small pool or lake for the use of their stock. Except on 

 the brows of the bluffs which enclose the valleys, this loam is thick enough 

 to make a reliable subsoil as well as surface soil. In some of the valleys it 

 is very thick, but here it is apt to be influenced by the causes that produced 

 the river-terraces and to mingle with the ordinary alluvium. On the up- 

 lands generally where it may not have been reduced by wash, its average 

 thickness might reach thirty feet, but in some of the valleys material of 



