Abstract The central Virginia Piedmont is underlain by complex igneous and metamorphic rocks, including: Paleozoic, Neoproterozoic, and Mesoproterozoic rocks of the suspect Goochland terrane; Early Paleozoic rocks of the suspect Chopawamsic arc terrane; Mid-Paleozoic successor basin deposits; and a suite of Taconic and Alleghanian plutons. Terranes are juxtaposed along a network of Late Paleozoic dextrally transpressive high-strain zones. The origin and significance of both the Goochland and Chopawamsic terranes remain a source of debate. The central Virginia Piedmont includes a distinct suite of commercial-grade mineral deposits including rutile-rich anorthosite, pegmatite, kyanite, and slate. The widely felt 2011 Virginia earthquake (M = 5.8) occurred along an unrecognized fault in the central Virginia seismic zone and demonstrates that old Appalachian structures are still active in eastern North America's modern stress field.

Abstract Conchostracans or clam shrimp (order Conchostraca Sars) are arthropods with a carapace consisting of two chitinous lateral valves. Triassic conchostracans range in size from 2 to 12.5 mm long and are common in deposits that formed in fresh water lakes, isolated ponds and brackish areas. Their dessication- and freeze-resistant eggs can be dispersed by wind over long distances. Therefore many conchostracan species are distributed throughout the entire northern hemisphere. In the Late Permian to Middle Triassic interval, several of these forms are also found in Gondwana. Many wide-ranging conchostracan species have short stratigraphic ranges, making them excellent guide forms for subdivision of Triassic time and for long-range correlations. The stratigraphic resolution that can be achieved with conchostracan zones is often as high as for ammonoid and conodont zones found in pelagic marine deposits. This makes conchostracans the most useful group available for biostratigraphic subdivision and correlation in continental lake deposits. Upper Triassic Gondwanan conchostracan faunas are different from conchostracan faunas of the northern hemisphere. In the Norian, some slight provincialism can be observed even within the northern hemisphere. For example, the Sevatian Redondestheria seems to be restricted to North America and Acadiestheriella n. gen. so far has been found only in the Sevatian deposits from the Fundy Basin of southeastern Canada. Here we establish a conchostracan zonation for the Changhsingian (Late Permian) to Hettangian (Early Jurassic) of the northern hemisphere that, for the most part, is very well correlated with the marine scale. This zonation is especially robust for the Changhsingian to early Anisian, late Ladinian to Cordevolian and Rhaetian to Hettangian intervals. For most of the Middle and Upper Triassic, this zonation is still preliminary. Five new genera, six new species and a new subspecies of conchostracans are described that are stratigraphically important.