It's the ponded water from these that may have been involved in cementing
the colluvium near the Little Colorado. My guess is that these basalt dams
would disappear relatively quickly once breached, because it would be easy
for the water to quarry pieces of the columnar basalt and carry it away.
Perhaps the smooth surface and conglomerate of Glen Canyon Concrete would
be less erodible.
These lakes are often dated to about 1my BP and they really leave very few
traces, compared, for instance, to Glacial Lake Missoula and to Lake
Bonneville. And their draining leaves very few traces compared to the
Channeled Scablands. If anyone knows of upstream traces of the Grand
Canyon lakes, I'd like to hear about it.
>
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