August 20-23, 2008
Click on the small picture to see an enlargement.
|Kim Bishop (right foreground), professor at CSULA, discusses the two possibilities for the origin of the Poverty Hills. An early explanation was that the hills were the result of transpressional compression at a left stepover along the Owen's Valley right-lateral fault. Bishop believes that the Poverty Hills are the remnants of a megalandslide and that the type of brecciation in the rocks is important in determining the correct solution.
||In this photo the group is studying roadcut exposures of the Pennsylvanian Keeler Canyon Formation. The rocks were brecciated and the goal of our observations was to determine if the breccia features observed were more likely formed in a landslide or in a fault zone. Bishop's arguments seemed persuasive. If the Poverty Hills were a landslide remnant, the slide would have to have come from the Inyo Mountains where the Keeler Canyon Formation is found and the slide would have to be more than 1,000 years old.
||In this photo, Kim Bishop shows us a segment of the Big Pine fault that has been cut by a stream channel. Because the stream channel has not been offset along the fault, it seems clear that the Big Pine fault did not move during the 1872 earthquake as claimed by others.
||Here, the group hikes along the alluvial terrace on the downthrown side of the Big Pine fault scarp. The alluvial terrace on the upthrown side of the scarp is on the left and higher than our heads. The extent of erosion on this scarp is clearly greater than the on the 1872 earthquake scarp on the Owen's Valley fault, which is another indication that the Big Pine fault did not move during the 1872 earthquake.
||Looking down from the alluvial terrace on the upthrown side of the Big Pine fault scarp to the group on the downthrown side of the scarp. The conclusion drawn from the morning's discussions was that the Big Pine fault is not structurally linked to the Owen's Valley fault. The Inyo Mountains are in the background.
||After our morning studies at the Poverty Hills, Doug Yule led us up into the Inyo Mountains to this lovely lunch stop where we feasted on our brown-bag lunches and soaked in a huge number of healthy solar rays.
||After lunch, Doug Yule (facing camera from behind the group) and Mike Kaericher (senior thesis student) described the significance of the rocks exposed along the ridge in the background. These rocks belong to the Neoproterozoic Wyman Formation. In the saddle on the right side of the photo are the brown, smooth-weathering, thin-bedded shale and carbonate beds of the typical Wyman Formation. Across the center of the photo are the slightly grayer, siliciclastic beds of the Hines Tongue of the Wyman Formation that was deposited in shallower water than the main Wyman Formation. On the left side of the photo are the more resistant, gray, blocky outcrops of the overlying Reed Dolomite.
||From the Inyo Mountains we traveled north to a quarry in the 760,000-year-old Bishop Tuff. Steve Lipshie (back to camera in blue shirt) found a shady place for us to stop while he told us about the rocks in the quarry cliff behind us. The oldest unit under our feet and behind our backs is stratified and represents an air-fall ash deposit. The more blocky, whiter, and unstratified unit above the heads of those on the right half of the photo is a pyroclastic ash flow deposit (ignimbrite). Above that is a second stratified air-fall ash, and above that, where the stratification ceases, is a second pyroclastic ash flow. It was interesting to learn that each of these units was deposited in only a few days.|
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