94 ABSTRACTS 



The appended remarks by Dr. Ells deal with the district to the 

 east and northeast of that studied by Adams and Barlow, and show 

 that here also the same series can be recognized and that the same . 

 relations between them obtain. 



The Origin afid Age of the Gypsum Deposits of Kansas. By G. P. 

 Grimsley. 



Among the minerals of economic importance in the state of 

 Kansas, gypsum occupies a prominent place, and it has attracted the 

 attention of geologists for many years. At the present time the state 

 stands first in the Union in value of its.gypsum product. The deposits 

 of ecomic value occur in a belt trending northeast-southwest across 

 the state with a length of 230 miles and in width varying from five 

 miles at the north to thirty-six miles iiear the southern line. There 

 are three important areas : northern, central, and southern. Intermediate 

 deposits connect the northern and central areas, while the interval 

 between the central and southern is occupied by salt beds. The 

 topography increases in ruggedness southward. In the northern area 

 three companies are engaged in plaster manufacture. There are six 

 mills in the central area, and two in the southern. The rock is white 

 or a gray mottled, with a saccharoidal texture in the upper portion, 

 but becomes more compact below. The dip is toward the west. In 

 the central area occur a number of secondary gypsum dirt deposits, 

 which form the basis of the greater portion of the plaster manufac- 

 ture. This material is a granular dirt of an ash-gray color. It is 

 soft, and readily shoveled into cars, so that it is ready for calcining 

 with less labor and expense than in the case of the solid gypsum. At the 

 present time four of these deposits are worked. Under the microscope 

 the dirt is seen to consist of a mass of small angular gypsum crystals 

 of varying size. Mingled with the gypsum crystals are small quartz 

 crystals, some calcite poorly crystallized, and traces of organic material. 

 The deposits are found in low, swampy ground near small creeks, and 

 strong springs occur in most of them. Usually there is a ledge of 

 rock gypsum at the same level, or ten to twenty feet below. The 

 gypsum beds are all Permian, ranging from the Neosho epoch to the 

 close, and they rise geologically to the south. The northern and 

 central rock gypsum deposits appear to have been formed in the same 

 gulf cut off from the western Permian sea ; while the gypsum dirt 



