A diverse flora has been discovered in a dark clay lens in upland gravel in southern Maryland near Brandywine. More than 49 taxa have been identified in the assemblage, which includes leaves, seeds, fruits, pollen, and a Taxodium (bald cypress) trunk. The vegetation is dominated by deciduous trees and vines. Four taxa are now absent from North America but survive elsewhere; one is extinct. A la...

Studies of the effects of the Central American Seaway’s closure on microfossil taxa and stable isotopes of foraminifera previously addressed the timing of emplacement of the Caribbean–tropical eastern Pacific sill, changes in marine nutrients, evolutionary and paleobiogeographic events associated with closure, and rates of uplift in Central America. However, there have been no quantitative stud...

The E-vergent Northern Apennines formed by Oligocene-Miocene convergence and westward subduction of Adria beneath Europe. Extension ensued in the Mid-Late Miocene reflecting lower plate roll-back causing opening back-arc Tyrrhenian Sea. Post-orogenic extension is commonly advocated as main driver exhumation belt's inner domain high-pressure/low-temperature (HP-LT) rock units. Acquadolce Subunit...

Recent geomorphic studies suggest that significant (∼1.5 km) late Cenozoic surface uplift occurred in the southern Sierra Nevada, a conclusion that is difficult to reconcile with recent stable-isotopic paleoaltimetry studies. Numerical modeling can play an important role in resolving this dispute. In this paper I use two models of bedrock channel erosion, the stream-power model and a sediment-f...