PLATE XLIII. 



RAMSEY COUNTY, 1888. N. H. WINCHELL. 



This is the smallest County in the state, containing only 187.15 square miles. 

 Along the bluffs of the Mississippi the Trenton limestone exists, underlain by the 

 St. Peter sandstone, the two together constituting an escai'pment which rises about 

 seventy-five feet above the river. These bluffs, however, below the mouth of the 

 Minnesota river, are obscured by the drift of the second glacial epoch and are much 

 smoothed by decay, and this is especially true below St. Paul. Above the mouth of 

 the Minnesota the gorge of the Mississippi is narrow, and has been cut since the 

 last drift was deposited. The highest parts of the Trenton are not seen at the imme- 

 diate river bluffs, but are so shaly that they have been worn back. They are found 

 in some of the short tributary gorges at St. Paul, at Finn's glen, in Reserve, and 

 were penetrated in the deep well drilled some years ago at the old Reform School, 

 in S. E. J sec. 34, Rose, and showed a total thickness for the Trenton, including the 

 limestone, of 138 feet. The St. Peter sandstone is 15.0 feet thick and extends below 

 the river level. 



This county is mostly covered by a morainic drift deposit, consisting of red till, 

 varying to gravel and sand derived from the red till. There is one important excep- 

 tion to this character of the till, viz., there is a morainic tract in Mound township 

 composed of gray till, analogous both in composition and in geographic place, 

 respecting the red till, to the gray till mounds seen in Marshan in Dakota county. 

 In both cases the surrounding country is covered by modified drift mainly of gravel 

 and sand, and the gray till mounds rise boldly and very conspicuously out of this flat 

 modified drift plain. The age of this gray till may not be the same as that which 

 is spread widely over the state west from Ramsey county, but it may date from the 

 earlier glacial epoch. 



The northern one-third part of the county is rather flat, and in the northeastern 

 it is plain that the ancestral lake from which White Bear, Bald Eagle and other lakes 

 are the derivatives, spread over much more territory, having deposited a fine, lami- 

 nated, gray clay which extends into Anoka and Washington counties, constituting 

 the subsoil over a wide tract, including Forest Lake and Centerville. This glacial 

 lake might be called lake Mahtomedi. A similar lake, which had a short duration 

 in Rose, has been named lake Hamline by Mr. Upham. 



Along the Mississippi river is a distinctly terraced contour. Besides the terrace 

 flat formed by the Trenton limestone, there is a gravelly terrace, most marked in 

 West St. Paul and extending into Dakota county, rising about fifty feet above the river. 



