Post-Piney Creek and Piney Creek Alluvium
Holocene, younger than 12,000 years. 3 crags on this site have their map point on it.
What the map says
Gravel, sand, silt, and clay of modern stream flood plains and slightly older low terraces less than 6.1 m above stream level. Deposits of Bear Creek, Clear Creek, and Boulder Creek, and South Platte River are coarse, cobbly gravel near the Mountain front; decrease in grain size downstream. In streams east of the South Platte River, deposits are mainly sand. Sand, silt, and clay compose the deposits in small streams and tributaries. Thickness generally less than 6 m. Minor source of sound aggregate.
1:100,000 sheet: Trimble and others, 2003, U.S. Geological Survey Geologic Investigations Series I-856-H (3 crags). A contact line at that scale is about 100 m wide on the ground.
Served by Macrostrat (CC BY 4.0). The wording is the map's own, quoted as a fact about the mapped unit, not about any one wall.