WOliK OF THE MINNESOTA SURVEY. 33.") 



In Marchf 1872, under enactment of the legislature, the regents of the 

 university of Minnesota were placed in charge of a geologic and natural 

 history survey of the state. In that same year a state geologist was ap- 

 pointed, who has been working under somewhat limited appropriations 

 to the present time. In order the more completely to carry out the 

 intent of the law. the regents also appointed in 1888 a state zoologist, and 

 in 1890 a state botanist. The publications of this survey thus far have 

 been a series of annual reports, the nineteenth of which is now in press) 

 several special bulletins ; and two volumes of the final report, all of which 

 are geologic except bulletins 3 and 4 and some special papers in the 

 annual reports. Much is contained in the annual and final reports by 

 X. II. W'inchell, state geologist, and Warren Upham and M. W. Harring- 

 ton, assistants, on the geology of the portion of the state discussed by the 

 writers. Wherever use is made of this material reference will be made. 



Finally. Warren Upham placed in the hands of one of the authors a 

 manuscript which contained ;i syllabus of his observations in this por- 

 tion of Minnesota up to the time of its preparation. It bore the date of 

 May 5, 1883. 



The upper Cambrian. 

 the potsdam sandstone. 



Tin pre-Paleozoic Floor of tin District. — The formations under consid- 

 eration were laid down upon a floor of Archean and Algonkian rocks. 

 This floor has been found below the Potsdam sandstone at Minneapolis, 

 Stillwater and Brownsdale, and without doubt much if not all of the 

 territory lying between those places and westward is underlain by the 

 granitic and gneissic rocks. Probably three divisions of the Algonkian 

 are represented. In the northeastern corner the Keweenawan diabases 

 pass under the sandstones and shales around Taylors Falls and have been 

 traced to Stillwater, where they lie 717 feet below the surface;- toward 

 the north and northwest the schists and associated eruptive granites dis- 

 appear beneath the feldspathic conglomerates of the Snake river; and 

 along the western side of the area the quartzites and arenaceous shales 

 of the red quartzite formation extend from Nicollet county southwestward 

 into [owa and South Dakota and were regarded as Huronian by James 

 Hall f and Dr. C, A. White;!; :tm ' subsequently by the Wisconsin geol- 

 ogists || and the members of the lake Superior division of the United 

 Stat.- ( reological Survey.§ 



* A. D. Meeds, Bull. Minn Acad Nat. Sci , vol. iii, no 2, 1891, p. 274. 

 TTrans. Am. Philoa Soe . ue« ser., \"i \iii. L866, p, 329. 

 i leologj ••! towa, vol. i, 1870, p. 171. 

 Geology <>r Wisconsin, vol. iv, 1873 78, p. 575. 

 g Irving and Van Hise, Bull. U S. Geol. Survey, no. 8, 1884, pp. 15, 34; C.W.Hall, Bull. Minn. Acad. 

 Nat. Sci., vol. iii, no. ^, 1891, p. 248. 



