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



337 



clay above it, and containing the remains of plants, as at the localities on the upper waters 

 of the Cottonwood, thirty or forty miles to the westward. The rock was exposed for some 

 ten or twelve feet, and I have no doubt but the same argillaceous and arenaceous beds 

 which are found below it on the Upper Cottonwood, lie beneath it at this place, and will 

 be found filling the interval between the sandstone seen here and the concretionary lime- 

 stone at Winkleman's farm, in the following order : 



1. Clay and soil with earthy coal ; 4 ft. 



2. Ferruginous, irregularly bedded sandstone with layers of plants, etc. ; about 10 feet visible. 



8. Slope (covered) to bottom prairie, probably covering the soft clays and sands which are penetrated in the shall on the 

 Upper Cottonwood ; 00 ft'. 



4. Level of bottom prairie ; 40 to 45 feet above the river level. Concretionary limestone with intercalated beds of marl ; 



18 ft. 



5. Red clays and marls with bands of concretionary limestone to river level. 



The question may recur as to the age of these lower beds, which possess a character so 

 entirely unlike the greenish clays and sands of the formation of the Cottonwood valley. 

 The color of the marls is similar to that of the lower exposures of the quartzite, being red 

 or brownish- red, with spots and stripes of Jighter color, giving a variegated aspect; and 

 the material was in all probability derived from the denudation of these ancient beds, 

 which became more argillaceous in their lower members. 



The concretionary interrupted layers of limestone in the marl gradually give place to 

 the heavy concretionary mass of limestone above, which is likewise interstratified with 

 greenish and red marls. 



In the absence of organic remains, and without a knowledge of the immediately subja- 

 cent strata, it would be injudicious to assign positively a geological age to these beds ; 

 still, since they arc apparently directly beneath the deposits which I have referred to the 

 Cretaceous, I infer that they may be not older than the Triassic formation; and probably 

 the red marls and superincumbent limestones represent the interval from the close of the 

 Pakcozoic deposits to the beginning of the Cretaceous period. 



This lower marl and limestone formation, as well as the clays and sands, together with 

 the ferruginous sandstone bearing plant remains, occur on both sides of the Minnesota 

 Piver from New Ulm northward ; and I have received information of the same series con- 

 siderably to the southward of this point. The ferruginous sandstone was seen by Col. 

 Pfaendcr near Fort Pidgely on the east side of the river ; and I have, since my return from 

 there, been informed that he has found the earthy coal near the same locality. The 

 formation is known to me as far north as the mouth of Beaver Creek ; and I believe it 

 will be found to underlie much of the country on the east side of the Minnesota, and 

 between that river and the Mississippi. 



VOL 



xiii.— 43 



