Back to the map for downtown

Next we go into downtown, where the foundation of the area changes some. These buildings here are built on the Broadway alluvium, and for some, the foundations go down into the bedrock Denver formation. Deeper into the Denver Formation is a major aquifer. It is an important water source for communities not tapped into the elaborate Denver Water Board system.

Looking at the map again, we can see the change in color as we go from ‘ed’ to ‘asa’, which is the Broadway alluvium, and Broadway alluvial terrace.

This is a river terrace cut, and is the old flood plain of the South Platte. The boundary is pretty clear as you drive north along Lincoln just pass Cherry Creek. There will be a hill on your right side from there at Speer until you pass 20^th Avenue. The lower part of your left is the Broadway Terrace.

In the Denver area Broadway alluvium is about 6-12 mm thick and consists about equal parts sand and gravel. The gravel is made up of granite, pegmatite, quartz and small amounts of gneiss and schist, and there are beds of clay mixed in various places.

The next few buildings are built on top of this alluvium.