ABSTRACTS OF PAPERS 97 



west across Kansas to a point in Cowley County not far from the Oklahoma 

 line. Determination of the elevation of the top of the granite from the records 

 of these wells and observations of many deep wells which have failed to reach 

 crystalline rocks have made possible the delineation, with considerable ac- 

 curacy, of the form of much of the buried granite surface. 



In eastern Kansas the granite surface slopes gently westward away from 

 the Ozark uplift, which has its eccentric high point in the Saint Francis Moun- 

 tains, south of Saint Louis, where the granite is exposed. The granite is ap- 

 proximately 1,01)0 feet below sealevel at Columbus, Cherokee County, in the 

 southeastern corner of Kansas, and nearly 1,500 feet below sealevel at Kansas 

 City. The inclination of the granite surface in this region appears to be fairly 

 regular and approximately equal to the dip of the overlying stratified rocks. 

 An irregularity of considerable importance, however, appears in the vicinity 

 of Yates Center, in Woodson County, where granite was encountered in a well 

 at a depth of 2,585 feet, while at Iola, Allen County, about 20 miles to the east, 

 a well 3,434 feet deep did not reach crystalline rocks, and another well, 10 

 miles northwest of Yates Center, was drilled to 3,557 feet without encounter- 

 ing the basement granite. The granite is very deeply buried in Greenwood 

 County and in the adjacent country to the north and south. 



The "granite wells" in central Kansas are located in a prominent belt of 

 anticlinal structure, with part of which is associated the important oil and gas 

 fields of Butler and Marion counties. The granite rises rather sharply and, as 

 now known, has the form of an elongate ridge marked by a number of high 

 points or peaks which are separated by intervening saddle. The highest part 

 of the buried granite ridge is near the north Kansas line, where crystalline 

 rocks approach to within 550 feet of the surface and attain an elevation of 

 nearly 600 feet above sealevel. To the south there is a rather low saddle, be- 

 yond which the granite surface rises beneath Morris and Chase counties in a 

 number of more or less prominent peaks. None of these, however, attain an 

 elevation equal to that of the granite north of the Kansas River. In northern 

 Butler County the crest of the ridge drops rather sharply, but rises beneath 

 both the Eldorado and the Augusta oil fields. Farther south the granite is 

 encountered only at increasing depths. 



The lateral slopes of the granite ridge have been ascertained at some points. 

 It appears that the east slope is considerably steeper (150 feet per mile, aver- 

 age) than that on the west (50 feet or less). At the present time data are 

 hardly sufficient to support strongly the suggestion that displacement by fault- 

 ing, with downthrow to the east, is responsible for the granite ridge. 



Studies of the relation of the sedimentary rock formations to the granite 

 ridge are incomplete, but it is evident that in some places rocks as young as 

 the uppermost Pennsylvanian are in contact with the granite. In some places, 

 chiefly in the saddles and on the flanks of the ridge, considerable thicknesses 

 of limestone belonging to the Mississippian and Ordovician intervene. There 

 was evidently important weathering and erosion of the pre-Pennsylvanian 

 formations in this region before rennsylvanian sedimentation. 



The major structural features which are observed in the sedimentary rocks 

 above the granite, as well as many of the minor anticlines and synclines, ap- 

 pear to be controlled by the underlying granite. The structure in general 

 VII— Bull. Geol. Soc. Am, Vol. 33, 1921 



