"Bob Noel" wrote:

How far down would you have to go to get to solid rock/ground suitable
for a foundation in New Orleans vs Seattle? For some reports I've
seen
the land around New Orleans has been sinking for years and it would be
difficult to raise up the level of the land.

That's because New Orleans used to be kept in place by the precarious
balance of two opposing forces. The city is constructed on 100 feet of
soft silt, sand and clay, and it naturally subsides several feet a
century. Historically, that subsidence has been counteracted by
sedimentation: new silt, sand and clay that are deposited when the river
floods. But since the levees went up-mostly after the great flood of
1927-the river has not been flooding, and sedimentation has stopped. In
addition, oil and gas explorers have cut numerous straight access canals
through the marshes around the city that speed drainage and reduce silt
deposition.

Marshes are not wasteland; they serve important hydrological and
biological purposes that make them worth preserving. If we do not learn
this, we will continue to create these intractable, slow motion
catastrophes.

--
Dan
C172RG at BFM