Tuesday, November 12, 2013

Geo 365: Nov. 12, Day 316: Delta Conjecture

Given my thoughts and comments over the last couple of days, on the nature of the terrace deposits, I decided to back up and show a more detailed shot of the modern Sixes River delta, just north of Cape Blanco. In particular, after recognizing the imbrication in Sunday's post (the latter of the links), I'm wondering if the Cape may be an example of inverted topography- a ridge representing a former channel filled with more erosion- and weathering-resistant materials. I've normally seen inverted topography in the form of mafic lava flows filling a valley. Erosion (in some cases) is then more effective cutting into the previous bedrock to either side of the former drainage, leaving it standing at relatively high relief. In this case, I'm wondering if perhaps the gravel "armor" in a former Sixes River channel has caused the same sort of effect, creating a resistant ridge and promontory headland.

For reasons I'll show and explain tomorrow, I think that's unlikely to be the case, but it's not out of the realm of possibility.

Photo unmodified. May 7, 2013. FlashEarth location.

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