Marine sediments exceptionally rich in organic carbon, known as black shales, occur globally but intermittently in well correlated Cretaceous successions. The presence of black shales indicates that sporadic, ocean-wide interruption of normal respiration of marine organic matter during oxygen-deficient conditions has occurred. Submarine volcanism on a massive scale, related to...
The geologic processes at work in American Samoa have long been a point of scientific debate. Of its numerous volcanic formations, few breach sea level, leaving an enormous proportion of their mass unavailable to traditional observation. This study aims to describe the deep sea geomorphology of American Samoa through compilation,...
Spike morphology characteristics and the free-threshing habit of wheat have been extensively investigated because of their evolutionary significance and practical importance. Several genetic systems that govern these traits have been reported. Some studies suggest polygenic inheritance while others have identified major genes. This study was conducted to identify and locate...
The increase in modern atmospheric CO₂ concentration (360 ppm) from
pre-industrial levels (280 ppm) raises concern over the impact of anthropogenic
carbon dioxide input on atmospheric chemistry. For this reason, it is important to
understand the natural fluctuations of atmospheric carbon dioxide in the past. The
Vostok ice core record...
The Cretaceous was a period of extreme climatic conditions accompanied
by major perturbations in ocean-atmosphere biogeochemical cycles. One of the
most intriguing features is the sporadic interruption of normal marine pelagic
sediment deposition by organic rich sediments deposited during oxygen-deficient
conditions (ocean anoxic events OAEs). A current model for the...
There is significant interest in the fabrication of nano- and micro-structured silica with spatially ordered features, which exhibit enhanced optoelectronic properties with application to the next generation of display devices, semiconductors, and sensors. Currents methods of fabrication employ top down processes which use extremes of temperature, pressure, and power. There...
Westward transport of water vapor across the Panama Isthmus helps to
maintain the salinity contrast between the Atlantic and Pacific Oceans, important in
thermohaline circulation and global climate. Relatively low sea-surface salinities and a
strong, shallow pycnocline in the eastern Pacific warm pool (EPWP) region near
Central America reflect high...