re: #271 Decatur Deb

Not just the old lake bed of Monteczuma’s time, but in an active earthquake zone. IIRC, the modern solution was to ‘float’ the buildings on unique foundations. Think Felix Candela was involved in the design.

Heavily saturated clays according to Wikipedia. With subsidence issues due to water being pumped out of them. Which in an active earthquake zone is like building on jello. I think Deb is correct about “floating” foundations for the large buildings - though the Wikipedia page for Felix Candela doesn’t mention it.

If it’s sand instead of clay the sand compresses to fairly high stability a couple hundred feet down. If I recall correctly one of the Brooklyn Bridge support piers is actually resting on sand instead of bedrock.

Interesting.
en.wikipedia.org

Developed in the 19th century - in Chicago. Another city building on top of old lake bed and deep soils.