At 8:07 a.m. EDT on 9 Aug. 2020 a M w 5.1 earthquake located ~3 km south of Sparta, North Carolina, USA, shook much of the eastern United States, producing the first documented surface rupture due to faulting east of the New Madrid seismic zone.The co-seismic surface rupture was identified along a 2-km-long traceable zone of predominantly reverse displacement, with folding and flexure generating a scarp averaging 8-10-cm-high with a maximum observed height of ~25 cm.Widespread deformation south of the main surface rupture includes cm-dm-long and mm-cmwide fissures.Two trenches excavated across the surface rupture reveal that this earthquake propagated to the surface along a preexisting structure in the shallow bedrock, which had not been previously identified as an active fault.Surface ruptures by faulting are rarely reported for M <6 earthquakes, and hence the Sparta earthquake provides an opportunity to improve seismic hazard knowledge associated with these moderate events.Furthermore, this earthquake occurred in a very low strain rate intraplate setting, where earthquake surface deformation, regardless of magnitude, is sparse in time and rare to observe and characterize.

Prepared in conjunction with the 2015 GSA Annual Meeting in Baltimore, Maryland, this volume contains guides to field trips in this historic region. Emanating from the Fall Line city of Baltimore, these trips reflect the diversity of geological features in the mid-Atlantic region including the Piedmont, Appalachian Mountains, and Coastal Plain, and the importance of geology on the development and construction of the Baltimore-Washington, D.C., metropolitan area. Trips to the core of the Appalachian orogen concern themselves with the tectonic and metamorphic history, early Paleozoic carbonate platform development, Devonian paleoclimate, and coal-mine fire hazards. Excursions to the Coastal Plain examine various aspects of Cenozoic stratigraphy, structure, barrier island formation, and wetland and ecosystem development. A variety of trips also explore urban geology, including building and monument stones of Baltimore and Washington, D.C., urban hydrogeology, and Civil War battlefield geology.

This volume includes 10 field guides that explore the diverse geology of the southern and central Appalachians. These guides examine both ancient rocks and modern landscape processes, highlighting new research ideas regarding these old terranes. Three guides focus on the geology of the Appalachian Plateau and Valley and Ridge, considering topics such as the enigmatic Eocene igneous rocks, the gas-rich Marcellus and Millboro Shales, and new models for karst formation. The 2011 M5.8 Mineral, Virginia, earthquake literally shook up our understanding of the Piedmont and two guides focus on new research in the epicentral region. Two guides take in the Paleozoic to Proterozoic geology of the Blue Ridge province. The volume is rounded out by three guides focused on Mesozoic geology, including the world-class Lagerst–tte fauna in the Dan River basin, a unique uranium deposit at Coles Hill, Virginia, and the tectonics of the Scottsville Basin.