^ 221 



buttonwood, seven of sassafras, five of magnolia, one fig, one palm, 

 and two of cinnamon. The last four were probably hardy species of 

 their kinds. Still they indicate a warmer climate than now exists. 

 When we le^ollect that at the period of their growth, this part of the 

 country was nearly on a level with the ocean, and the dry land was com- 

 prised principally of a few islands, the variance of the climate is easily 

 explained. These are " the first known of the great modern group of 

 Angiosperms,'' "and the ordinary fruit-trees of the temperate zones,'' 

 for leaves of the Fyrus and Frunus, allied to the pear and plum, have 

 also been found. 



The contrast between this fossil flora and the plants of the older for- 

 mations is very strong, while its resemblance to those now living is 

 equally remarkable. The interest attached to this numerous variety of 

 modern plants is enhanced by the fact that in the earlier formations no 

 dicotyledons are found, the conifers which come down from the De- 

 vonian age being the highest type. But in our Dakota and the corre- 

 sponding age in Europe we have a sudden influx of new types covering 

 nearly all the forms now living. The large proportion of orders and 

 g-euera to species is very remakable. The numerous indications show- 

 that the trees must have grown on islands near the shore-line, and that 

 the le_aves were imbedded in the marine sediment immediately after 

 dropping. Worm-borings are also found in the same strata with the 

 leaves. A few fish and one saurian {Hijposaurus vehbii) have been 

 found in this group. 



In the Dakota group, there are a few veins of brown lignite, which is 

 always an inferior variety of coal. The most important seam extends 

 irregularly, and with frequent omissions, from the State line in Wash- 

 ington and Kepublic Counties, southwesterly to the Arkansas Yalley 

 It varies in thickness from 10 inches to 10 ; but usually a portion of this 

 thickness includes seams or layers of clay-shale. This lignite contains 

 a large percentage of ashes; but a more objectionable feature is its 

 tendency to crumble on exposure to frost. This alone renders it almost 

 worthless as a marketable coal. At some localities it has much 

 pyrites, with sulphur so free as to cover the deposit with a yellow 

 coating This coal sometimes takes fire by spontaneous combustion. 

 Notwithstanding these defects, it becomes of value in sparsely- tim- 

 bered counties, by furnishing to the settlers a cheap fuel, costing only 

 the time and labor necessary to dig and convey it to their farms. It is 

 usually mined at the surface in the open air, by "stripping," L e. remov- 

 ing the few feet of soil or shale that overlies it. An average outcrop 

 will yield at least a ton for a day's labor. It is found in Washington, 

 Kepublic, Cloud, Mitchell, Lincoln, Ottawa, Saline, Ellsworth, McPher- 

 son, Kice, Barton, and perhaps some adjoining counties. The average 

 width ol the Dakota is less than fifty miles, being somewhat less than 

 that in the north part of the State, and more on the Smokv and Arkan- 

 sas Kivers. The dip is to northwest and very slight. It is difficult to 

 decide the amount, but it does not appear to be on the avera^^e more 

 than o feet to the mile. It is conformable to the Fort Hays lime forma- 

 tion above it. It corresponds very nearly to the Cretaceous of Swal- 

 low s Kepoit, p. 9, and also to Nos. 2 and 3 of his Triassic* The 

 maximum thickness of this group may be 500 feet. It is difficult to 



estimate the thickess, as the larger portion of the materialconsistsof sand- 

 stone, much of which was originally thrown down in oblique deposits. 

 nnT: ^^ ^^^^^ thickness of the Cretaceous in Kansas we estimate to be 

 960 teet. • 



*The other numbers of his Triassic belong to the Permio-Carboniferous. 



