R Brown's video: Stevens Canyon Land Slide Tectonic Block Part 3

Last week, I ventured to the bottom of the landslide area below Stevens Canyon Road / Canyon Trail. This time, let's find out what happens when that landslide dams up the creek. Simple answer, you get a lake and maybe many lakes over the millennia. The slide dams the creek and water backs upstream. Water from upstream hits the backed up water and starts dropping it's sediment load. Over time, the canyon floor is filled side to side with sediment. Once the water backs up to the top of the landslide dam, it starts cutting down through that material. The dammed up lake slowly drains and eventually, the creek cuts a new channel through the newly deposited sediment in the canyon. Over time, the creek erodes the base of the landslide on the North American plate, a major earthquake on the San Andreas fault triggers another landslide and the story repeats. Judging by all the layers visible in the creek bank, this may have happened many times, since it's unlikely that there would be this much sediment deposited in any one event. Further evidence of multiple landslide dam events is the existence of the old Canyon Road on the 1895 USGS historical topo map. That road crossed the creek at about the same place the modern Canyon Trail does. This is one of the only places where you can easily cross the creek due to it being filled with sediment. That road pre-dated the 1906 earthquake and landslide, thus the canyon was likely in a similar state before 1906. This is my hypothesis for what has happened in this section of Stevens Creek to explain the flat nature and deep sediment here. Also ties in the anecdotal evidence from the 1973 geology paper. Paper: ENVIRONMENTAL GEOLOGIC ANALYSIS OF THE MONTEBELLO RIDGE MOUNTAIN STUDY AREA: https://openlibrary.org/works/OL68916... Pg. 22 mentions a landslide associated with the 1906 earthquake and this is ground zero for that slide. In fact, the report mentions that slide extended for 1/2 mile, nearly a kilometer, along the canyon. USGS National Map Viewer w/ Hill Shade layers: https://apps.nationalmap.gov/viewer/ Layering Diagram: Kenneth A. Bevis http://www.intheplaygroundofgiants.com/geology-of-sedimentary-rocks/ More to come... Subscribe for more content like this Comment, rate, share & click the bell icon And as always, thanks for watching