The formation is composed of sands, clays and carbonates which are interbedded. The sands are light gray to olive gray and poorly consolidated. They are clay-like with some dolomite with a very fine to medium grained phosphate component. Carbonates are usually light gray to yellowish dolomite found in outcroppings. The dolomites are soft to hard with variably sandy, clay-like, phosphate components with opaline chert often found. The phosphate content is high enough to warrant mining.USGS: Hawthorn Group, Peace River Formation, Bone Valley MemberUSGS: Geologic units in Hillsborough county, Florida
