HISTORICAL SKETCH. 107 



1873-82, Present survey.] 



SEC. 8. It shall be the duty of the said board of regents, through their president, to make, on 

 or before the second Tuesday in December of each and every year, a report showing the progress 

 of the said surveys, accompanied by such maps, drawings and specifications as may be necessary 

 and proper to exemplify the same to the governor, who shall lay the same before the legislature ; 

 and the said board of regents, upon the completion of any separate portion of the said surveys, 

 shall cause to be prepared a memoir or final report, which shall embody in a convenient manner 

 all useful and important information accumulated in the course of the investigation of the par- 

 ticular department or portion ; which report or memoir shall likewise be communicated through 

 the governor to the legislature. 



SEC. 9. To carry out the provisions of this act the sum of one thousand dollars per annum 

 is hereby appropriated, to be drawn and expended by the [said] board of regents of the University 

 of Minnesota. 



SEC. 10. This act shall take effect and be in force from and after its approval. 



The present writer was appointed to conduct this survey in July, 1872, 

 but, having work to complete in the state of Ohio, did not begin service 

 till September. The field-work the first year occupied about a month and 

 was closed by the first heavy fall of snow, November 12th. The means 

 placed at the disposal of the state geologist not warranting the employment 

 of assistants he was only able to make a general reconnoissance of the 

 southern and central portions of the state accessible by railroad, and on 

 this as a basis he was enabled to give a nearly complete section of the strata 

 from the trap and granitic rocks to the Galena limestone in the Lower 

 Silurian, including also about forty teet of the latter. Various out-crops 

 of the Cretaceous were described also in the first annual report. 



On the basis of the field-work done in the fall of 1872, and of reports 

 already published, the first annual report of the survey gives a general 

 sketch of the geology of Minnesota, as then known, accompanied by a small 

 colored geological map of the state, and also a chart of geological nomen- 

 clature intended to express the relation of Minnesota to the great geologi- 

 cal series of the earth, and the probable equivalency ot some of the names 

 the formations have received in the various states and in Europe. 



In the account of the "Potsdam sandstone" of the northwest, as 

 defined by the Iowa and Wisconsin geologists, and of the red quartzytes of 

 the same region, the first step was taken toward the investigation of that 

 stratigraphical problem which seeks to determine the western equivalent 

 of the Potsdam sandstone of New York ; and inasmuch as the same name 

 had by good authorities been applied to two different and quite distinct 

 western formations, the name St. Croix was suggested for the light-colored 

 sandstone of the upper Mississippi and St. Croix valleys, it being more 

 probable that the Potsdam of New York was represented in Minnesota by 

 the red quartzytes and shales underlying. 



