BROWN AND REDWOOD COUNTIES. 577 



Cretaceous beds.] 



boulders of granite, gneiss and schists, up to six feet in diameter. The remaining 10 feet are 

 curved, contorted, and irregularly interstratificd. red, yellow, green and gray clays. They are free 

 from gravel, but contain flat, limy concretions, in some portions abundant up to one inch in 

 diameter, and elsewhere joined in sheets a foot or less in length and a half inch or less in thick- 

 ness, conforming with the stratification. These strata are eroded and covered unconformably by 

 the drift. 



In Sherman, Redwood county, Prof. Winchell records an exposure of Cretaceous beds of 

 sandy marl, hoiizontally stratified, seen in the road that descends from the Lower Sioux Agency 

 to the ferry. At this place in 1860 Prof. A. W. Williamson found in a cut for the road about 30 

 feet above the Minnesota river a large coiled shell, since lost, which agreed nearly with the figure 

 of Ammonites monilis seen in an English text-book of geology. 



About four miles farther northwest, or half way from the Lower Sioux Agency to Redwood 

 Falls, a Cretaceous outcrop, including a thin layer of lignite, occurs in the south bluff of the 

 Minnesota valley, above Tiger lake, being in the southwest corner of section 35, Ilonner, some 

 three-quarters of a mile west from the mouth of Crow creek. Mining for the exploration of the 

 lignite, which is an imperfectly formed coal, of inferior quality, yet valuable for fuel, was under- 

 taken here, on land of George Johnson, in 1871, by William II. Grant and others, a horizontal 

 drift, or adit, being excavated into the bluff to a distance of about 260 feet from its face south- 

 ward. This followed the seam of lignite, which, or at least a black lignitic shale, was found con- 

 tinuous along all this distance, being level in the direction of the adit, but dipping to the west 

 about three degrees, or five feet in a hundred. The adit is about a third of the way up from the 

 foot to the top of the bluff, or some 60 feet above the river. Several tons of coal, sometimes quite 

 clear for a thickness of six to nine inches, were obtained from the mine, and were used as fuel. 

 The cost of the work, however, was about $2000, without discovering any portion of the bed that 

 could be profitably mined. 



Professor Winchell describes the formation here explored, and the similar lignite layer in the 

 bluffs of the Redwood river, a-t follows: " Tliis coal is from one of those layers in the Cretaceous 

 that are usually known as lignites. It is earthy, passing sometimes into a good cannel coal, or 

 into a bituminous clay. The compact cannel coal is in detached lumps, and occurs throughout a 

 band of about four feet in thickness. This lignitic baud was followed in drifting into the bank at 

 Crow creek, and was found to divide by interstratification with black clay, showing some leafy 

 impressions and pieces of charcoal. 



" The 'coal' here is said to overlie a bed of lumpy concretionary marl In some 



of the concretions are small shining balls of pyrites Over the 'coal' is a blue clay, 



requiring a timbered roof in the tunnel. This clay is likewise Cretaceous. The underlying 

 lumpy or concretionary white marl becomes siliceous, or even arenaceous, the concretions appear- 

 ing more like cheit. Some of it is also pebbly, showing the action of water currents. 



"The same lignite coal occurs near Mr. Johnson's, on the land of Hugh Curry, Wm. II. 

 Cornell, E. O. King and Mr. Hiker, in the little ravines that enter the Minnesota, the exposures 

 being kept fresh by the freshet waters. More or less exploring and drilling, besides that done by 

 Mr. Grant, has been engaged in, in this vicinity, but never with any better success. 



"Near Redwood Falls, on land of Mr. Birney Flynn, is another outcrop of carbonaceous de- 

 posit in the Cretaceous. This is seen in the left bank of the Redwood river. It is in the form of 

 a black bedded clay or shale, five or six feet thick, more or less mingled with charcoal and ashes, 

 the whole passing below into charcoal fragments mixed with the same ash-like substance. In 

 the latter are sometimes large pieces of fine, black, very compact coal, the same as that already 

 spoken of at Crow creek, as cannel coal. These masses show sometimes what appears to the eye 

 to be fine woody fiber, as if they, too, were simply charred wood. Further examination will be 

 needed to determine their origin and nature. They constitute the only really valuable portions 

 of the bed, the light charcoal, which everywhere shows the distinct woody fiber, being generally 

 mixed with the light ashy substance, and in a state of fine subdivision. 



"A short distance above Mr. Flynn's land is that of George Iloughton, where the Redwood 



Falls coal mine was opened. This mine consists of a drift into the bluff, forty feet, following a 



lignite, or charcoal bed in the Cretaceous. The bed here is seven feet thick, the greater part of 



it being made up of black, bedded shale or clay, though Mr. Flyim is authority for the statement 



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