• What to do: In 1894, the 251 acres of Riverview Park were donated to the City of Allegheny, which was later absorbed into the City of Pittsburgh. Long before that, however, the region was part of a vast tropical rain forest where coal swamps, rivers and an inland sea dominated the landscape. On Nov. 23, while leading an easy hike on park trails, Carnegie Museum geologist Albert D. Kollar explains how to recognize ancient rocks and find the fossils within. Participants take a look at geological features and rocks from the last Ice Age, and each hiker gets a copy of "The Geology of Riverview Park" guide book. 1:30-3:30 p.m., $15 Venture Outdoors members, $25 nonmembers.

• Contact: Venture Outdoors at 412- 255-0564, www.ventureoutdoors.org.