Continental biodiversity gradients result not only from ecological processes, but also from evolutionary and geohistorical processes involving biotic turnover in landscape and climatic history over millions of years. Here, we investigate the evolutionary and historical contributions to the gradient of increasing species richness with topographic complexity. We analysed a dataset of 418 fossil r...

Newly available data indicate that dams fragment the fluvial system of the continental United States and that their impact on river discharge is several times greater than impacts deemed likely as a result of global climate change. The 75,000 dams in the continental United States are capable of storing a volume of water almost equaling one year’s mean runoff, but there is considerable geographi...

Groundwater is considered a major source of drinking water and its quality a basis for good population health. In order to identify groundwater hydro-chemical characteristics and pollution conditions in Songnen Plain, groundwater hydro-chemical characteristics and nitrate-nitrogen (NO3-N) spatial distribution characteristics and the health risks were analyzed. Results showed that groundwater hy...

A late Eocene erosion sudace of low relief, which extended throughout south-central Colorado, provides a post-Laramide, pre-Oligocene, regional structural datum. The age and geomorphic character of the sudace are documented for an area of more than 10,400 km2 in the southern Front Range, Rampart Range, South Park, Thirtynine Mile volcanic field, southern Mosquito Range, upper Arkansas River val...

Abstract The Wupu cemetery, located in the Yizhou District, Hami City, Xinjiang Province, and eastern part of southern foothills Tianshan Mountains, is remains from late Bronze Age. In this study, four faience beads excavated cemetery were examined by stereomicroscopy, synchrotron radiation micro-CT, electron microprobe analysis. appearance compositions these are presented discussed. results sh...

The wind characteristics of the mountainous environment in Western China are extremely complex. Many advances have occurred study plains or hilly areas. However, some limitations remain mountain passes and riverbanks. We selected a pass river beach certain area as research objects, then set up observation instruments at different locations to establish temporary stations collect more than one y...

Using Magellan SAR images and the Schaber et al. [1998] crater data base we examined impact craters in the area north of 35øN and determined the geologic units on which they are superposed. The crater density of the regional plains with wrinkle ridges (Pwr) was found to be very close to the global average and thus the mean surface age of the plains is close to the mean surface age of the planet...

Aquifer overexploitation could significantly impact crop production in the United States because 60% of irrigation relies on groundwater. Groundwater depletion in the irrigated High Plains and California Central Valley accounts for ~50% of groundwater depletion in the United States since 1900. A newly developed High Plains recharge map shows that high recharge in the northern High Plains result...

Playas are ephemeral, closed-basin wetlands that are hypothesized as an important source of recharge to the High Plains aquifer in central USA. The ephemeral nature of playas, low regional recharge rates, and a strong reliance on groundwater from the High Plains aquifer has prompted many questions regarding the contribution and quality of recharge from playas to the High Plains aquifer. As a re...