. Bulletin of the Geological Society of America. Geology; Geology -- United States. 56 D. WALCOTTâA DISPLAt EMENT IN THE GRAND ' West. East. /,. . - -âr. â â I-"- '"I- : Figubi '.'.âA Restoration of Section 8. ting the block forming Chuar lava hill before the Tertiary faulting and erosion of Chuar valley and the Grand ' iafion. The lettering i* the same aa in ~<-< g. from the vertical to the west, and the cast branch is nearly vertical : a fact that serves to explain the Tertiary movement following the latter, as it was mainly a vertical displacement.
. Bulletin of the Geological Society of America. Geology; Geology -- United States. 56 D. WALCOTTâA DISPLAt EMENT IN THE GRAND ' West. East. /,. . - -âr. â â I-"- '"I- : Figubi '.'.âA Restoration of Section 8. ting the block forming Chuar lava hill before the Tertiary faulting and erosion of Chuar valley and the Grand ' iafion. The lettering i* the same aa in ~<-< g. from the vertical to the west, and the cast branch is nearly vertical : a fact that serves to explain the Tertiary movement following the latter, as it was mainly a vertical displacement. '/'//< pre-Cambrian Movement.âThe westward throw of the pre-Cambrian AJgonkian) fault, varied at differenl points from tOO to 4,000 feet, owing to its traversing strata that dip both with and against its strike. All along its line, except in Nun-ko-weap and Chuar valley- and across the Colorado opposite Clinar valley, the strata on the eastern Bide are now concealed by the carrying down of the Tonto and superjacent rocks by the Teniary move- ment. In sections 1. '_', -s, and 9the pre-Tonto strata an' shown on each side of the fault, and on the east Bide of Chuar valley the beds of the Chuar group are -'en lying up against the west side of the lava hills, mi the line of the oblique western branch of the fault I fig. s i. To the Bouth the fault pa-- - through a -addle eroded through the Tonto sand-tone between the hill south of Chuar lava hill and the main ridge. This proves that the fault crossing the saddle, with a throw of from 1,200 i" 1,500 feet, is of pre-Cambrian , as the line nf the Tonto sandstone ha- been scarcely more than broken by the slight reverei movement that occurred during Tertiary time on the main fault and it- eastern branch. In every instance where strata of the (huar group approach the fault the beds are flexed up toward- it on a tad Bcale, ;i- shown in Bectione I. â¢Â». ii. 7, ami 8. Bach from the displace- ment this flexure disappears b
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