Bulletin Volume 351-354 (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. Excerpt: ...as far as I am aware this reference has not been changed essentially by the somewhat later researches of Professor Smith. Relation to adjacent formations.--The general dip of the Swearinger slate is to the southwest beneath the Hosselkus limestone, and on this account it was at first supposed to be older than the Hosselkus limestone. In the Redding quadrangle of Shasta County, where these Triassic rocks are extensively exposed and much less disturbed, Prof. J. P. Smith discovered that the Pseudomorwtis horizon, corresponding to at least part of the Swearinger slate, is above instead of below the Hosselkus limestone.c A study of the same region as set forth in the Redding folio confirms us in the same opinion, and shows that in the Taylorsville region the Triassic has been overturned, reversing the natural order of superposition. Everywhere the Swearinger slate and the Hosselkus limestone are essentially conformable. In the Taylorsville region they do not appear coextensive, but this lack may be due to displacement. The only other sedimentary formation with which the Swearinger slate comes in contact is the Robinson, and judging from their faunal relations, belonging, respectively, the one to the top of the Triassic and the other near the top ofthe Carboniferous, they must be in unconformable contact, and the discordance must represent a time interval of long duration, an interval which is represented in the Redding region, as ahead)' explained, by a great thickness of lavas overlain by 1,500 feet, chiefly of shales--the Pit formation, belonging to the middle Triassic. The conformity of the Swearinger slate anil the Hosselkus limestone and the unconformity of both on the Robinson formation is shown in fig. 5, A and B, which illustrates a section near Robinson's p...