• Tropical Sea Surface Temperatures Over the Last 120,000 Years

    Sea surface temperature (SST) is one of the most important and fundamental components of Earth’s climate. Tropical SST determines the location of the Intertropical Convergence Zone where the northeast and southeast trade winds meet, and influences global moisture content, the strength of monsoons, and precipitation in the tropics.  Therefore, the importance of understanding the changes [...] Read More

  • Evolution of a Cretaceous Subduction Model: Insights from the Catalina Schist

    The Catalina Schist crops out on Santa Catalina Island and underlies the southwestern California borderland, preserving a Cretaceous subduction zone environment. The Catalina Schist consists of amphibolite-facies rocks atop a suite of rocks metamorphosed at progressively lower temperatures with increasing depth. This inverted metamorphic sequence has been explained to be the result of tectonic juxtaposition [...] Read More

  • U/Th Dating of Cold Water Tufa Deposits from Kimberly Region of Australia

    Paleoclimate records from Indonesia and the West Pacific Warm Pool (WPWP) reveal that changes in global and regional climate have altered the intensity and location of Indonesian-Australian Summer Monsoon (IASM) precipitation over glacial/interglacial cycles (Magee & Miller, 2004; Griffiths et al., 2009; Mohtadi et al., 2011). Understanding the magnitude and timing of monsoon variability in [...] Read More

  • A 4,000 Year Stalagmite Record of Extreme Rainfall Events in Tropical Western Australia

    Global environmental change poses several risks, including the possibility of increased frequency and strength of severe weather events. Though extreme weather events are difficult to define precisely, they include, but are not restricted to, tropical cyclones (a.k.a. hurricanes and typhoons) and particularly intense rainfall episodes within summer monsoons. However, the main problem associated with present [...] Read More

  • Paleoclimate Reconstruction in Portugal and the Iberian Margin

    Paleoclimate reconstructions for Portugal and the Iberian margin have recently been conducted for the last glacial cycle with the main focus centered on both terrestrial and marine-based data. Portuguese stalagmites provide climatic information through oxygen and carbon isotopes in stalagmite calcite and can be dated using uranium-thorium techniques. One area of particular interest is the [...] Read More

  • Mud Layers in Stalagmites: A Proxy for Past Cyclone Activity

    Our current understanding of trends in tropical cyclone activity in the Indo-Pacific is restricted by a limited historical record.  Mud layers deposited in stalagmites during flooding events in cave KNI-51 from tropical Western Australia appear to be a proxy for tropical cyclone activity in the region.  Aragonite stalagmites were precisely dated using U/Th mass spectrometry [...] Read More

  • Monsters & Gigantism: Exploring Large Body Size

    Large body size in movie monsters has inspired a new generation of scientists to explore the fact that real animals, both extinct and extant, have attained almost comparable sizes throughout geologic time. In this study I look at gigantism as preserved in the fossil record and at biologic problems arising from attaining a large size. [...] Read More

  • Characterizing Pyroxene Cooling Rate Using Reflectance Spectra

    Pyroxenes are among the most common minerals in the inner solar system. The degree of order/ disorder in their crystal structure relates to the cooling history of the mineral. In pyroxenes, Fe2+ prefers the M2 cation site, and Mg prefers the M1 cation site in the crystallographic structure; the slower the pyroxene cools, the more [...] Read More

  • High-fluid Component in Some Recent Lavas from the Southern Cascades

    We present U-Th and Sr isotopic data on young (Holocene) lavas from Lassen and Mt Shasta volcanic fields and surrounding areas.   Andesitic lavas from Shasta have 232Th/238U ratios of 2.6–2.7 and, similar to those reported previously, have activity ratios  (230Th/238U) of 1.01–1.03 close to secular equilibrium. A Holocene rhyodacite flow from Lassen has a 232Th/238U [...] Read More

  • Reconstructing Tropical Cyclone Frequency Using Mud Layers in Speleothems

    Our ability to understand multi-decadal to centennial-scale trends in tropical cyclone activity is limited by the short duration of, and limitations in, historical records. In order to extend these records for tropical Western Australia, we have analyzed mud layers in stalagmite KNI-51-11 from the Kimberley region of north-central Australia that appear to be formed by [...] Read More

  • Beach Dynamics of San Salvador

    The San Salvador Island, Bahamas, is located within Hurricane Alley, causing the island to be passed by approximately 60 hurricanes in over a 100-year span.  The purpose of this project is to conduct a comparative multiyear study, from 1999 to 2010, of three beaches on San Salvador that experience different wave and wind regimes and [...] Read More

  • Monsoon Variability Preserved in Australian Stalagmites During the Early Holocene

    Recent studies from Borneo and Indonesia have increased our understanding of the evolution of the Indonesian-Australian Summer Monsoon (InAuSM) system over the past 10,000 years (the Holocene epoch).  However, little is known about the InAuSM in Australia or at centennial time-scales. Here we present carbon and oxygen stable isotope data from two stalagmites collected from [...] Read More

  • Efficacy of the Curaçao Marine Park: A Pleistocene Perspective

    As global climate change persists, anthropogenic impacts will continue to exacerbate current environmental degradation, particularly to coral reef ecosystems. To mitigate this critical situation, coral reef conservation efforts have focused on the development of effective marine protected areas (MPAs). However, successful ecological conservation and restoration require an understanding of previous community states – unaffected by [...] Read More

  • Tectonic History of the North Qaidam Ophiolite, Qinghai Province, China

    The North Qaidam Ophiolite provides insight into the mechanisms that formed the rocks of the Tibetan Plateau before its uplift through the Cenozoic India-Eurasia collision. The ophiolite, juxtaposed and folded with an ultrahigh-pressure (UHP) terrane across the Luiliangshan Detachment Zone, separates the two major terranes in the region, the Qaidam and Qilian blocks. Two endmember [...] Read More

  • Fire History from Little Round Lake, Northwestern Wisconsin, USA

    Fire history recorded in charcoal in lake sediments can be used to determine different climate conditions and vegetation, as well as fire frequency.  The observation of different charcoal morphotypes has been suggested to reflect fuel sources and burn conditions present at the time of the fire. I classified and counted charcoal from Little Round Lake, [...] Read More

  • Pleistocene Rapid Sea Level Change in Western Australia

    Climate change affects sea level causing sea level fluctuations, which are correlated to glacial and interglacial periods. During glacial intervals water is stored as ice on the continents; therefore, sea level drops. When temperatures increase during interglacial periods, the melting ice sheets return the water to the ocean basins thereby raising sea level. These intervals [...] Read More

  • Trace Elemental Analysis of a North Australian Stalagmite

    A 152 cm tall stalagmite (KIM1) was collected from the El Niño-Southern Oscillation (ENSO)-sensitive and monsoon-dominated Kimberly region of northwestern Australia. In order to better constrain the results of a previous a stable isotope study of KIM1, we conducted 173 trace elemental analyses at 1 cm intervals, corresponding to ~20 year resolution. Mg/Ca and Sr/Ca [...] Read More

  • Speciation in Fire Corals: What Constitutes a Species?

    Two morphologies of Millepora, currently classified as separate species, exist off the coast of the Bahamas. Millepora complanata is found primarily in shallow waters, possessing wide, smooth branches whereas Millepora alcicornis is found primarily in deeper waters, possessing thinner, knobby branches. Upon discovery of colonies that contain intermediate morphologies, the question arose as to whether [...] Read More

  • Big Bend National Park, Texas: an Educational Spring Break

    In 2008, Cornell College’s Geology Club helped sponsor a trip for twelve students to Big Bend National Park in Texas. Big Bend hosts an array of impressive geologic features recording disparate events from Cretaceous deep-sea deposition to volcanic flows less then 30 million years old. This presentation will present a short history of the park’s [...] Read More

  • Sector Zoning and Age in Zircon Grains from the Western Gneiss Region, Norway

    Zircon is a strong mineral capable of withstanding extreme geologic pressures and temperatures. It is able to retain geochemical signatures. which allow the timing of geologic events to be determined. The Western Gneiss Region of Norway is one of the largest exposed complexes of ultrahigh-pressure metamorphic rocks in the world. By determining the ages of [...] Read More

  • Speciation in the Millepora Complex: What Constitutes a Species?

    Fire coral from the genus Millepora are ubiquitous in tropical western Atlantic reefs. Two distinct morphologies of Millepora, currently classified as separate species, exist off the coast of the Bahamas. M. complanata have broad, smooth blades and prefer shallow waters whereas M. alcicornis have knobby branches and prefer deeper waters. After an intermediate morphology was [...] Read More

  • Skeletal Morphology of the Genus Millepora Displays Phenotypic Plasticity

    The genus Millepora, commonly known as fire coral, is a calcareous hydrozoan common in tropical seas worldwide. In the western Atlantic, there exist two prominent morphologies that are presently being classified as separate species. Millepora alcicornis is defined by thin nodular branches; Millepora complanata has plate like, smooth blades. However, recent genetic data suggest that [...] Read More

  • Onshore/Offshore Trends in Preservation of the Cidaroid Subfamily Cidarinae

    Echinoid tests are composed of a series of plates, interlocked with adjacent plates, and reinforced by soft tissue. Regular echinoids disintegrate in a generally predictable manner: spines disarticulate, followed by oral and aboral membranes, the lantern, and finally the corona which will break apart progressively. Cidaroid echinoids are characterized by having a small degree of [...] Read More

  • Race and the Pullman Company, 1913- 1948

    The Pullman Company shaped the traveling experience of generations of people in the US, starting in 1867 and continuing for 102 years. Soon after the Civil War, Pullman was one of the first industrial firms to hire former slaves. The Pullman Company was later the site of the first black labor union in the country [...] Read More

  • U-Th Chronologies of Stalagmites from Two Caves in Western Portugal

    Stalagmites from two caves, Almonda Cave and Glory Hole Cave, located near Nazare in westcentral Portugal, are being investigated in order to reconstruct the region’ s paleoenvironmental history. Here we report our initial attempts to construct growth histories for these samples using U-Th mass spectrometry. Most stalagmites from Almonda Cave, one of the deepest and [...] Read More

  • Taphonomic Comparison of Modern and Pleistocene Coral Assemblages:

    Taphonomic analyses of reef corals have been conducted in multiple reefal environments present in a great many locations including the Great Barrier Reef, Florida Keys, Bahamas, and Papua New Guinea. However, taphonomic research on modern and Pleistocene reefs of Western Australia has not been published. The study presented here examines taphonomic signatures retained by modern [...] Read More

  • An Ozark Stalagmite Record from the Penultimate Deglaciation

    We present stable isotopic data from CS-04-5, a 54 cm-high, cylindrical calcite stalagmite from Cosmic Cavern, northwest Arkansas, which grew during the penultimate deglaciation (Termination 2). The chronology for CS-04-5 is based on six U-Th mass spectrometry dates, all of which fall in correct stratigraphic order (140.6±1.9, 138.5±2.6, 137.4±2.1, 136.0±2.5, 134.2±2.0, and 128.7±2.4 ka). Petrographic [...] Read More

  • Genetic Analysis of Fire Coral

    Coral are important components of underwater ecosystems and contribute to reef biodiversity. The Millepora genus (fire coral) is a hydrozoan represented predominately by two species prevalent on tropical western Atlantic reefs. Each species has distinct morphological features: M. complanata is broad, smooth, and blade-like while M. alcicornis is thin with knobby branches (Kaplan, 1982). However, [...] Read More