The city was built on a place where two types of soil meet: sandy soil and marine clay.
The sandy soil pushed against the marine clay, accumulating and forming hills over several centuries.
This island is composed mostly of unconsolidated material such as glacial till, marine clay, and sand.
The hotel sits on a raft foundation with thick marine clay below the soil.
Sinking pilings into the soft marine clay to build an underground parking lot raised construction costs.
Fossil remains of marine life have been found in marine clay formed during that time.
Construction in marine clays thus presents a geotechnical engineering challenge.
Swelling of marine clay has the potential to destroy building foundations in only a few years.
Later on, they found marine clay mixed with seawater even in the deeper underground.
After this withdrawal, the region was covered by the Champlain Sea, which left a layer of marine clay.