St. Peter's Sandstone. 



117 



ing a section as observed at Prairie du Chien, he notes the 

 presence of a sandstone underlying a buff colored limestone 

 and called "soft saccharoid sandstone." It is stated to be 

 made up of sharp, angular fragments of quartz, scarcely 

 cemented together. It may be white or colored, and when so 

 colored it is often strongly cemented. It is compared to 

 coarse, common, unrefined sugar, and, though it is difficult to 

 break of! a piece without its crumbling to pieces in the hand, 

 yet, in places, it crops out extensively, and seems to stand 

 the weather as well as other strata which are used for build- 

 ing stone. It is here given a thickness of forty feet, although 

 Dr. Locke says he did not see the base of the formation. In 

 the section accompanying the paper this sandstone is repre- 

 sented as lying between a blue limestone (now recognized as 

 Trenton) and the Lower Magnesian limestone.* In the 

 description of the strata from the Blue Mounds to the Wis- 

 consin River, this sandstone is again referred to as the same 

 as seen at Prairie du Chien. " It is remarkable for having 

 its upper surface at an exact and even plane, very nearly 

 level. In an excavated area, where several ravines meet in 

 the same valley, and with the eye at any point of the upper 

 surface of this sandstone, all other points appear at the same 

 plane, like an emptied lake, leaving a line of ice to mark its 

 original height ; even where the rock is covered by earth, 

 the vegetation changes so abruptly in sort and color, at the 

 surface of the sandstone, that the line may still be distinctly 

 traced."! 



On November 2, 1842, a paper by Dr. D. D. OwenJ was read 

 before the Geological Society of London. It was read in 

 April of the following year before the American Association 

 of Naturalists and Geologists. Dr. Owen notices the pres- 

 ence of a sandstone underlying conformably a blue fossilifer- 

 ous limestone. The sandstone is sometimes of a deep red 

 and sometimes of a white color, and resembling loaf sugar. 

 Beneath this succeeds a magnesian limestone." He also says 

 he has never found any fossils in the sandstones. || This for- 



; Ibid, p. 123. 

 flbid, p. 124. 



| On the Geology of the Western States of North America. Am. Jour. Sei.. Vol. 

 XLV., pp. 151-152, 163-165 ; Quart. Jour. Gcol Soe. London, Vol. II, pp. 443-447, 1846. 

 I Ibid, p. 446. 



