Depends on how the towers footers were constructed. Sometimes they drill down to bedrock, sometimes they just drive pilings into loose soil to a certain depth to stabilize the footings. I do not know how it was done, but if pilings, they may have just excavated down below them during the cleanup.
But this photo does look really weird. No scrap/chisel or blast marks. This looks washed and formed by lava or water erosion. I've never seen this picture before.
Depends on how the towers footers were constructed. Sometimes they drill down to bedrock, sometimes they just drive pilings into loose soil to a certain depth to stabilize the footings. I do not know how it was done, but if pilings, they may have just excavated down below them during the cleanup.
But this photo does look really weird. No scrap/chisel or blast marks. This looks washed and formed by lava or water erosion. I've never seen this picture before.
It was formed by water erosion; frozen water. The bedrock beneath NYC was scoured by the ice sheet as it flowed SE during the last glacial epoch.