Quarry Lake Park (Racine) Reef Outcrops

Geologic map of Racine Quarry Lake Park showing locations of reef cores.
© The Field Museum - CC BY-NC

Geologic map of Racine showing locations of Silurian reefs in the Racine Formation.
© The Field Museum - CC BY-NC

An area of massive reef core bordered by inclined flank beds. Typical example of reef flank beds, which dip downwards from right to left in this outcrop at Racine County Quarry Lake Park. (Silurian reef Racine Dolomite.)
© The Field Museum - CC BY-NC

Crinoid grainstone flank beds at Racine County Quarry Lake Park. When crinoids die, their skeletons separate into broken lengths of stem and hundreds of small plates. This bedding surface shows crinoid stems surrounded by abundant debris of small, separated plates. The actual skeletal material has been dissolved from the rock, and the stems and plates are preserved as hollow molds. Reconstruction of the crinoids as they appeared in life. Death and decay of immense numbers of crinoid individuals produced the beds of crinoidal debris at Quarry Lake Park.
© The Field Museum - CC BY-NC

Detail of massive reef core with thin bedded, slightly dipping crinoid grainstone flank beds in Racine Formation at Racine County Quarry Lake Park. The orange stain is derived from weathering of the mineral marcasite, which is present in small amounts in the dolostone. R eef flank beds at Quarry Lake Park contain abundant crinoid fossils. In the southeast corner of the quarry, these beds are nearly horizontal, in contrast to their inclined orientations in much of the outcrop.
© The Field Museum - CC BY-NC

Orthoconic nautiloid cephalopod in Racine Formation at Racine County Quarry Lake Park.
© The Field Museum - CC BY-NC