Bulletin of the Geological Society of America . t an earlier date, before the present Drumheller channelshad been eroded, glacial waters also continued directly southward to passthe east end of Saddle Mountain anticline as well. Channeled scablandand stream gravel with granitic material cover 150 square miles of theregion south of the end of this fold. As in the Palouse scabland, hillsof mature topography and deep soils, developed in a weak sedimentary(presumably the Ellensburg formation) above the basalt, flank the scab-land and are isolated in it. Some of the glacial waters entered Esquatzel
Bulletin of the Geological Society of America . t an earlier date, before the present Drumheller channelshad been eroded, glacial waters also continued directly southward to passthe east end of Saddle Mountain anticline as well. Channeled scablandand stream gravel with granitic material cover 150 square miles of theregion south of the end of this fold. As in the Palouse scabland, hillsof mature topography and deep soils, developed in a weak sedimentary(presumably the Ellensburg formation) above the basalt, flank the scab-land and are isolated in it. Some of the glacial waters entered EsquatzelCoulee and some went by way of Koontz Coulee to the Columbia nearRinggold. Indeed, Esquatzel Coulee below Council has been eroded inthe scabland subsequent to the maximum flooding. The waters around the tip of the Saddle Mountain anticlinal nosenever cut deeper than 900 feet above tide, while the head of the syn-clinal course just below the Drumheller plexus is eroded in basalt to 700 596 J. H. BRETZ GLACIAL DRAIXAGE OX COLUMBLl PLATEAU a . M;. 700 Figure 8.—Part of Drumheller Channels PlexusChannels indicated bj^ arrows ; rock-basins in black. THE SPOKANE GLACIATIOX feet above tide. Using the criterion of tains accnmulation, most of theBrnmheller channels and the existing synclinal river valle}^ date fromthe Wisconsin glaciation, while the spillway aronnd the east end ofSaddle Mountain was formed during the Spokane glaciation. Chan-neled scabland also lies east of the youthful Drumheller channels and ata higher altitude. It apparently belongs to the Spokane spillways. It appears^ therefore, that when Spokane waters escaped southwardfrom the Quincy basin there was no noteworthy valley for lower CrabCreek and, as in the Palouse country, the flood spre«id out and found itsway among the hills of weaker rock. These hills were removed in theDrumheller tract for a width of more than 10 miles. South of SaddleMountain the width of the scoured tract is equally great. The floodseparat
Size: 1337px × 1869px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1890, booksubjectgeology, bookyear1890
