. Report of a geological survey of Wisconsin, Iowa, and Minnesota : and incidentally of a portion of Nebraska Territory : made under instructions from the United States Treasury Department . m introduced on theopposite page. It seems as if the alternate thawing and freezing on the sunny sidehas caused a more rapid decay of the rock, which scaling and splitting off, sometimesin large masses, slips down the side of the hill; this, together with the rapid transitionfrom heat to cold on the southern exposure, probably prevents trees from coming tomaturity on that side; or, it may in part be due to
. Report of a geological survey of Wisconsin, Iowa, and Minnesota : and incidentally of a portion of Nebraska Territory : made under instructions from the United States Treasury Department . m introduced on theopposite page. It seems as if the alternate thawing and freezing on the sunny sidehas caused a more rapid decay of the rock, which scaling and splitting off, sometimesin large masses, slips down the side of the hill; this, together with the rapid transitionfrom heat to cold on the southern exposure, probably prevents trees from coming tomaturity on that side; or, it may in part be due to some more general law, that hasregulated the elevation of these Magnesian Limestones in determinate lines; thrust-ing the beds up to the north of the line, while a depression occurred on the south. In some instances the hills seem as if split down the middle, one side being leftstanding whilst the other had been entirely carried away. La Grange Mountain,at the head of Lake Pepin, introduced on page 46, and the Cap de Killio, belowthe Wabasha Prairie, may be cited as examples in point. There is a striking analogy between the physical features of the country occupied OF THE by the Lower Magnesian Limestone, and that of the district further south, in Wis-consin and Iowa, where the Upper Magnesian Limestone is the surface rock; thereason is, both rocks are so nearly alike in chemical composition, that they undergosimilar changes by atmospheric agencies. There is scenery on the Upper Iowawhich is almost a fac-simile of views on the Little Makoqueta River in the DubuqueDistrict, where the rock is the Upper Magnesian Limestone. Both regions presenta combination of rural beauty characteristic of a considerable portion of the UpperMississippi. It is such as fixes itself strongly on the feelings of its inhabitants, andtends to endear to them the spot of their nativity. The soil derived from the decomposition of the Lower Magnesian Limestone isusually of excellent quality; ri
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Keywords: ., booksubjectbotany, booksubjectgeology, booksubjectpaleontology
