220 



Dakota groups have been collected witliiu 35 feet vertically and oue- 

 lialf mile horizontally. 



The material of this deposit is formed very largely of brown and varie- 

 gated sandstone, of all degrees of compactness, from that which crumbles 

 in the handling to that which requires a sledge-hammer to break it. 

 This extreme hardness is, in most cases, owing to the presence of iron, 

 in the condition of oxide and silicates. Sometimes poor limonite is seen. 

 In some places, in every county where it abounds, it affords a good build- 

 ing-material. It is frequently interstratifled or overlaid by clay-shales,- 

 of almost all colors. Many ledges give concretions of fanciful forms, 

 sometimes hollow, or with the center filled with loose sand. Some of 

 the hollow concretions are sufficiently large to be used by the farmers 

 as feeding-troughs for hogs and cattle. In a few localities they assume 

 the form of tubes of various sizes, some being 3 inches in diameter and 

 3 to 8 feet in length. These concretionary deposits are sometimes glazed 

 and distorted, as if they had been subject to the accion of fire; but the 

 cause is the oxidation of iron, and not any application of heat. Such 

 specimens of sandstone frequently inclose well-preserved dicotyledonous 

 leaves. 



The fossils of the Dakota are very unequally distributed over its area. 

 In searching for the marine mollusks, we have found but two localities, 

 both in the western part of Saline County, in the vicinity of Bavaria. 

 In one of these spots, covering a few acres, we procured twelve species 

 new to science. These are figured and described in Professor Meek's 

 work on the Invertebrates, now in press. The other locality furnished 

 a less number. 



In collecting fossil leaves, we have frequently examined every visible 

 outcrop for fifteen or twenty miles without finding a specimen 5 then 

 jDcrhaps a single square mile would j)resent several good localities. In 

 this irregular manner we have collected specimens from Washington 

 County to Fort Larned, a distance of one hundred and fifty miles. The 

 fossil plants are usually obtained from thin layers, or strata, extending 

 in a horizontal position along a ravine or around a hill. They may occur 

 at several places in the same vicinity, but usually without any connec- 

 tion. The fossil flora is almost entirely represented by leaves, though 

 a few specimens of fruit, imperfectly preserved, have been collected; 

 also some poor fragments of wood and bark. The leaves, however, are 

 usually in excellent preservation, the veins and veinlets as they lie im- 

 printed on the stone being frequently as clearly visible in all their out- 

 lines as those just taken from the living tree. 



Professor Lesquereux has recently made a report, issued by the De- 

 partment of the Interior, on the Fossil Flora of the Cretaceous Dakota 

 Group, which is one of the most valuable monographs published in our 

 country. He describes one hundred and thirty-two species, distributed 

 among seventy-two genera and twenty-three orders, of which one hundred 

 and seven species of nineteen orders and fifty- two genera are dicotyled- 

 onous plants. Of these, more than one-half have been collected in 

 Kansas; and about twenty of the new species were described by Pro- 

 fessor Lesquereux from specimens discovered by the writer. To these 

 are to be added twenty-six new species described by the same author in 

 a recent bulletin (YII of No. 5, second series) of Haydeu's reports. Ad- 

 ditions to these are constantly being made. They are found at all depths 

 in the Dakota, from within 35 feet of the Permian to within 40 feet of 

 the Fort Hays limestone. 



Although 'all the species are extinct, yet nearly all the of genera are now 

 existing, and all are of marked modern type. There are eight species of 

 conifers, five of poplar, six of willow, eight of oak, six of platanus or 



