How does the coastal bluffs map relate to a surficial geology map?
Coastal bluffs always occur in sedimentary deposits. These deposits are shown on a surficial geology map. Coastal bluffs can be found in all types of surficial deposits including the glaciomarine Presumpscot Formation (silt and clay), glacial outwash sand, glacial till (sand and gravel) and other surficial units on a surficial geology map. Glacial tills are generally more resistant to erosion than fine sand or the Presumpscot Formation, so the combination of maps can provide a more complete picture of where bluffs are and what they are made of.
