Transactions of the Geological Society of South Africa Volume 5, Nos. 1-4 (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. 1903 Excerpt: ... and communicating directly with the sea. In other words, in a shallow tidal lake. 3. If this gradual subsidence theory be adopted as correct, we must moreover make up our mrnds to very considerable unconformability between the different layers in the formation, for it would be most unreasonable to suppose that a gradual subsidence could lake place along a main axis of subsidence extending from Boksburg to Klerksdorp so regularly and in such a manner that from one end to another Of this stretch of country the various beds would be laid down on the top of each other with anything approaching to absolute regularity. I am satisfied, in fact, that the more we investigate the exact relations of these beds to each other, the more shall wo come to the conclusion that such uncohiformability is the rule and not the exception in the Witwatersrand banket formation."' Dr. Becker (p. 16, Witwatcrerand Banket) says: "It is sometimes assumed that the beds were laid down horizontally. For a small area such an assumption is justifiable enough, but it is quite insufficient, even as a rough approximation, when one is dealing with beds a score of miles or many scores of miles in length. One has only to recall the beaches of any coast line with which one is familiar, to perceive that bights, points, shallows, and deeper basins, are almost certain to occur within a dozen miles, while islands as well as coastal sinuosities are of frequent occurrence, particularly in a subsiding area." These deductions so ably worked out, may well shake one's belief in the theory of the granitic upheaval of at one time continuous horizontal beds, and to my mind they afford sufficient reason for the adoption of the subsidence theory. THE ZWARTKOP Mr. Draper asks: What is the Zwartkop...