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group of the Cretaceous. At this quarry, which has been recently opened 

 for the purpose of obtaining good building-materials, which are hauled to the 

 Winnebago village, I saw for the first time that intercalled quartzite bank 

 which is mentioned in the same report of Dr. Hayden, page 46. He de- 

 scribes it " as a very compact quartzite, the hardest and most durable rock in 

 the State, found all along the hills opposite Sioux City." At this quarry the 

 stone is of a dark grayish color, generally in two banks, one 4 feet thick, the 

 other, above, 2 to 3 feet, with an interlaying of a few inches of hard clay. 

 The lower is the more compact, hard as flint, giving fire by percussion, and 

 therefore difficult to break. It contains fragments of leaves, some entire and 

 well preserved, with distinct nervation ; all, at least all those which I have 

 seen, extended flat in the plane of stratification. This bank is underlaid im- 

 mediately and without transitional modification of the materials in contact 

 by soft-grained sandstone, easily cut with the knife, marked at different local- 

 ities by rough Indian sculptures of animals, &c, which, as remarked by Dr. 

 Hayden, {loc. cit.,) appear doubtless portions of the hieroglyphical history of 

 the Indian. This lower sandstone is more or less exposed in proportion to 

 the amount of detritus and alluvial covering its base. The best exposition ot 

 it is from 20 to 25 feet. Above the quartzite the sandstone is more ferrugi- 

 nous, darker, and hard. It has generally rare impressions of leaves ; but just 

 above Warner Quarry, under the thin coating of humus which covers the top 

 of the hill with vegetation, the remains of plants are in greater quantity than 

 I had seen them anywhere else in the vicinity. This place is little more 

 than one mile from the locality where No. 2 is exposed at the same level, 

 and therefore it appears that the fossil leaves do not become less abundant in 

 the upper part of the Dakota group. The whole section of the Warner 

 Quarry is 60 feet. Quite near Iowa City, the upper strata of the same group 

 are intermixed with beds of impure lignite, a matter without any value as com- 

 bustible, and the sandstone underlying them is blackened by an immense 

 mass of roots and rootlets of fluvial plants. This appearance is most like 

 that of the clay strata underlying beds of Tertiary lignite, or of the true coal of 

 the Carboniferous epoch. In this last case the remains in the under clay- 

 beds are leaves of Stigmaria ; in those of the Tertiary coal-beds, they are 

 evidently roots and rootlets of water-plants, recognized especially by the 

 tubercles and rhyzomas of the Equisetum. At Sioux City the roots in the 

 clay-beds are mostly undeterminable. They are mixed with fragments of 



