Abstract The Carmel Church Quarry fossil site in central Virginia has yielded thousands of vertebrate fossils over more than two decades of excavations conducted by the Virginia Museum of Natural History. The exposure of marine sediment here includes a highly fossiliferous bone bed within the Calvert Formation. Unlike most fossil finds from this formation along the Potomac River, the majority of fossils collected are from in situ deposits. The exposed section at Carmel Church includes Paleocene to Pliocene sediment, with vertebrate fossils also having been recovered from the Eocene Nanjemoy Formation. Common fossil finds within the Calvert Formation are typically isolated shark teeth, especially of Isurus (mako sharks) and Carcharhinus (requiem sharks). However, many large teeth of Carcharocles megalodon have been found as well. The ancient shallow sea ecosystem also supported a diversity of bony fish, reptiles, birds, and marine mammals. Carmel Church is the type locality for the mysticete (baleen) whale, Eobalaenoptera harrisoni, and has produced numerous other cetacean taxa. In addition, 28 species of diatoms have been identified from the site, further correlating the fossiliferous zone of the Calvert Formation to Bed 15 of other localities. The Carmel Church site also has one of the richest land mammal faunas of the Calvert Formation, particularly for the upper section, including fossil horses, tapirs, and peccaries. Despite intense excavations over many years, the site is still producing a large volume of fossil material, allowing participants the opportunity to help contribute to new discoveries from this fascinating locality.

Abstract The 295-300 Ma Petersburg batholith in east-central Virginia forms one of the largest and northernmost of the Alleghanian plutonic complexes in the southern Appalachian Piedmont. The batholith is primarily composed of granite including massive and foliated (both magmatic and solid-state fabrics) varieties. The plutonic complex intruded medium-grade metamorphosed volcanic/plutonic rocks of the Roanoke Rapids terrane. The western edge of the batholith experienced right lateral transpressional deformation associated with movement on the Hylas fault zone during the Alleghanian orogeny; this was followed by normal faulting and exhumation during the development of the Triassic Richmond basin. Much of the batholith was buried by a thin veneer of primarily Cenozoic siliciclastic sediments at the western edge of the Atlantic Coastal Plain. Granite rocks of the Petersburg batholith have long been quarried for both dimension and crushed stone. The purpose of this trip is to discuss the age, origin, and tectonic significance of the Petersburg batholith.

Abstract The siege of Petersburg and Richmond during the American Civil War in 1864–1865 provides a stellar example of how geology can affect military operations and thus the course of history. During the Union drive to take the Confederate capital, they used Virginia’s broad tidal rivers on the Atlantic Coastal Plain as supply lines for their huge army. During the siege, both sides took advantage of the unconsolidated Cenozoic sediments of the Coastal Plain to create a new style of combat—trench warfare—which would be taken to horrifying extremes in World War I. This trip visits seven sites of both historic and geological significance in the Petersburg area.