Bulletin of the University of Texas Volume 25-29; Scientific Series (Paperback)

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1913 Excerpt: ...small. Dolomite with minute open spaces was noted at 1600, 2476, 3355 and at from 4035 to 4065 feet below the surface. The upper part of the dolomite is known to consist, in part, of heavy beds. At the depth of 1600 feet a single piece of core was taken out which measured sixteen feet. A core of this length would have been broken in the process of cutting, if there had been any marked horizontal seams of bedding in the rock from which it.was taken. Chemical Composition. The dolomitie character of the rock is known from the fact that it is throughout comparatively resistant to dilute hydrochloric acid, nearly every sample having been tested in this respect. It is also known from the crystalline texture seen in nearly two hundred thin sections. Though this texture mostly is fine it is seen, in sufficient magnification, to be of the kind which characterizes all dolomities. A sample from the depth of 2264 feet, which to the unaided eye appears very much like limestone, was readily identified as dolomite by its optical properties. An analysis of the same sample made by Mr. S. H. Worrell, Chemist of the Bureau of Economic Geology and Technology, was accompanied by the note that the sample was a mixture of sulphate of lime and the double carbonate of lime and magnesia. This analysis is as below. Analysis of a Piece of Core from the Depth of 226k Feet in the Spur Boring, Spur, Dickens County, Texas. Lime as sulphate of lime 30.19 Lime as carbonate of lime 29.34 Magnesia as carbonate of magnesium 22.24 Undetermined 18.24 Clastic, Texture. The process of dolomitization has left much of the original clastic structure of these sediments in a condition yet to be made out. While the rock consists of minute dolomite crystals, the change has not yet obliterated the forms o...