FROM ST. PAUL TO THE WESTERN TART OF THE STATE. 



339 



in its northern prolongation, rises to the height of four hundred feet or more above the 

 level of the prairie at its base ; and I have every reason to believe that the structure and 

 character of the northern portion is similar to that farther to the south. 



I infer, moreover, that the high Coteau or Plateau, as represented on the maps between 

 the James River and the Missouri River, will be found to be a synclinal of Iluronian 

 quartzites and other rocks of that period* and that the modern geological formations of 

 the valleys on either side are in eroded anticlinals. 



It has heretofore been supposed that the palaeozoic rocks extended into this part of Min- 

 nesota ; but the existence of so large an area of Pre-silurian formations, and the relations 

 oj:' these rocks to the modern formations, would apparently preclude the extension of the 

 older fossiliferous rocks in this direction. 



In offering this brief sketch to the scientific public, I can only regret that time and 

 opportunity could not have enabled me to give a more complete exposition of this part of 

 the country. The few facts observed, however, may serve to direct observation, and in 

 some degree, perhaps, modify our views respecting the extent of certain formations. I 

 deem it of some interest to have determined that these, often isolated, patches (usually 

 called uplifts) of metamorphic quartz rock, with frequently a granitic aspect, have a struc- 

 ture, stratification, dip, and direction, and that they may be incorporated in our maps in 

 accordance to some system of geological and topographical expression. 



In making my investigations in the neighborhood of Redstone Ferry, I have been 

 much indebted for kind attention and valuable- information to Mr. Francis Baascn and 

 Mr. C. T. Clothier, of New Ulm, who volunteered to accompany me to several interesting 

 localities, which might otherwise have escaped my attention, and who gave me informa- 

 tion of other points of interest which for want of time were not examined. 



* It has become very important in the study of the geological structure of the continent, particularly in its 

 northern portions, to distinguish the highly crystalline rocks of the Huronian and Laurentian periods ; since their 

 accumulation and foldings, and subsequent denudation, have given rise to a different topography for each one. 



NOTE.— The discovery of this groat extension of the Cretaceous system to the north and northwest, combined 

 with our previous knowledge of its distribution in the region farther to the west, induces the bolicf that the for- 

 mation may at one time have been continuous ; and even now in some parts of the country, the easterly exposures 

 of these strata may be connected with those further to the west. Again ; the extension of the Cretaceous deposits 

 along the Mississippi Valley nearly to the mouth of the Ohio, and some bods of the same or a little later age in 



