One of the most compelling modern applications of paleoecological research focuses on utilizing subfossil assemblages to determine the impact of human activity on shallow marine environments. The extent of anthropogenically-mediated changes, however, cannot be determined without a pre-disturbance ecological baseline against which the altered state may be compared. To overcome this limitation, paleoecologists rely on … [Read more…]
Sedimentary properties can affect many aspects within the marine environment. It can affect everything from the way benthic organisms live to the pollutants causing changes to the environment. Some organisms prefer to live in more carbonate sediments while others prefer siliciclastic. The properties of sediments can be used to test the metal concentrations of the … [Read more…]
Climate proxies are any biological or geological record that preserves temperature or precipitation fluctuations prior to human records. This project’s climate proxy is stalagmites, which are cave formations created from drip water on a cave floor. In particular, this study focuses on carbon isotopes, which record vegetation and moisture changes, spanning parts of the last … [Read more…]
This project compares trends in the abundance of trace elements from the lanthanide series of rare earth elements (REE) from five garnets from the ultrahigh-pressure metamorphic Tso Morari Complex (TMC), Ladakh Province, NW India. Raw trace element abundance data were obtained by McElroy in 2013, using laser ablated-inductively coupled plasma mass spectrometry, and plotted in … [Read more…]
Due to its elevated temperatures and atmospheric CO2 concentrations, the Pliocene warm period (PWP) (5.3-2.6 million years ago) is a common analog for a future, warmer world. The El NiñoSouthern Oscillation (ENSO) is an ocean and atmosphere phenomenon punctuated by El Niño and La Niña events, changes in the distribution of warm water across the … [Read more…]
This research compiles beach profiling data obtained yearly between 1999 and 2016 and indicates annual changes in the beach morphology of three beaches on San Salvador Island, Bahamas. The profiles provide a visualization of the effect of different hydrodynamic regimes present on each beach. The beaches surveyed are each affected differently by wind- and wave-energy … [Read more…]
The trilobites of the genus Ceraurus have always been relatively uncommon. I chose to conduct research on this particular trilobite genus as I feel that the genus has been somewhat overlooked and I believe there is still a lot which we do not know about its members. In this research, I looked at the morphology … [Read more…]
Trace elements, including the rare earth elements (REEs) and Y, constitute low concentrations (<0.1%) of bulk rock compositions. These elements do not control growth, but instead record metamorphic events through zonation patterns in garnets. For example, heavy rare earth elements (HREEs) tend to be concentrated in the core of the garnet because they are preferentially … [Read more…]
Nitrates and other farm chemicals are transported from farmers’ fields into nearby streams. Nitrate levels have grown so high that they are likely the cause of hypoxia (lack of oxygen) in the Gulf of Mexico. Although methods to control the spread of farm chemicals have been implemented, it can be hard to determine if these … [Read more…]
Paleoclimatology is the study of past climates through the use of climate proxies, geologic or biologic records that preserve evidence of temperature or precipitation prior to those periods recorded by humans. Stalagmites, mineral deposits formed from dripwater on the floor of caves, are useful as paleoclimate proxies for two reasons. First, they can be precisely … [Read more…]
Western Russia has warmed at nearly twice the global rate over the past century; however, despite it being a major center of agricultural production, the hydrological response to such warming has not been well constrained. This investigation analyzes Mg and Sr variations in a U-Th dated stalagmite from the Volga Basin of the Southern Ural … [Read more…]
Layer-bounding surfaces in stalagmites represent hiatuses in growth due to either erosion during wet climate periods (type E layer-bounding surfaces) or a period of lesser deposition when climate is relatively arid (type L layer-bounding surfaces; Railsback et al., 2013, Int. J. Spel., 42, 167). Accounting for layer-bounding surfaces not only offers an additional method of … [Read more…]
The idea that human activity is driving recent global climate change has gained scientific consensus and entered the public spotlight. It is up to scientists such as paleoclimatologists to understand the nature of climate change and how the activities of people might affect it. The goal of paleoclimatology – the study of past climates – … [Read more…]
Pirates of the Caribbean: Dead Men Tell No Tales (2017) Duration 129 mins Genre Action, Adventure, Comedy, Fantasy. In Cinemas May 23, 2017 Language English. Country United States of America. Plot For Pirates of the Caribbean: Dead Men Tell No Tales Movie ‘Pirates of the Caribbean: Dead Men Tell No Tales’ was released in May … [Read more…]
Baywatch (2017) Duration 116 mins Genre Action, Comedy. In Cinemas May 12, 2017 Language English. Country United States of America. Plot For Baywatch Movie ‘Baywatch’ was released in May 12, 2017 in genre Action. Seth Gordon was directed this movie and starring by Dwayne Johnson. This movie tell story about Devoted lifeguard Mitch Buchannon butts … [Read more…]
In this study, I conducted research on the cause and effect relationship between Hyaenodon’s body size and the fluctuating climate throughout the Eocene and Oligocene. Hyaenodon is an extinct genus of mammals that belonged to a group of carnivorous creodonts called Hyaenodontidae. My focus will be the study of Hyaenodon’s teeth, a proxy for body … [Read more…]
Climate Leaf Analysis Multivariate Program (C.L.A.M.P.) is a program that allows us to score the leaf fossil characteristics of angiosperms to generate a paleoclimate record with respect to mean annual temperature (MAT). The experiment is a comparison between the C.L.A.M.P. record and the Paleosol record for the Miocene flora found in Oregon. The test will … [Read more…]
A review of existing literature was done to understand how ice interacts with rock, specifically in Alpine mountains when permafrost is present. Due to recent global climate change, permafrost has been melting at an increasing rate. This melting is causing talus slopes and various types of landslides to occur. It is through studying the rock-ice … [Read more…]
There have been three major groups of dogs: the hesperocyonines, the borophagines, and the canines. The former two groups both diversified, dominated a niche as hunters of large prey, and then declined to extinction in turn. This radiation and subsequent decline of dog clades mirrors a wider pattern in faunal succession of large predators throughout … [Read more…]
Summer monsoons provide the majority of annual precipitation in much of the global tropics. In northern Australia, the hydroclimate is dominated by the Indo-Australian Summer Monsoon (IASM). This monsoon provides 70-90% of yearly rainfall, all within the austral summer, supporting agriculture and regional ecosystems. Historical records of the IASM began in the late nineteenth century … [Read more…]
The Rummells-Maske site, 13CD15, lost within the memories of those who originally excavated it back in 1968, may be seen once again. With the archeology field classes’ efforts in 2012 and 2014 and the guidance of professionals from the department of the state archeologist of Iowa, this site may once again be observed and studied. … [Read more…]
Deformities such as pathologies and pseudopathologies found within fossil specimens can be informative about an ancient species. One species in particular about which we still know far too little is Carcharodon megalodon (the largest shark species in history). In this study I examined the types of pathologies and pseudopathologies and their frequency in C. megalodon … [Read more…]
The evolution of equids (horses) has been extensively studied and is often used as an example of how evolution occurs, and has many times been used to prove that evolution does in fact occur. Horses appear in North America early in the Eocene at about 55-50 Ma. The story of horse evolution in North America … [Read more…]
Coral populations have declined significantly over the past few decades in a phase shift towards macroalgae. Until the advent of white-band disease in the early 1980’s, Acropora cervicornis was a dominant coral in reefs throughout the Caribbean. In an effort to determine precedence for such a die-off, scientists tested for a signature in the Pleistocene … [Read more…]
Rubies are one of the four rarest gemstones on earth, but we understand little about their geologic formation. Knowing the formation of rubies is important in many ways, as it could increase our ability to find and mine more rubies as well as improve our understanding of their chemical complexities. Furthermore, knowledge of the geological … [Read more…]
Marking the southwestern coast of Europe, the Iberian Peninsula (IP) is a hotspot for studying transitions of climatic signals from high-to-mid latitudes, because it is a sensitive region to abrupt climatic variations. There are numerous paleoclimate studies on marine cores from the Iberian Margin that reveal synchronous changes in SST inferred from isotopic ratios (O18/O16) … [Read more…]
During the Cenozoic era, the North American Great Plains are known to have held some of the most diverse populations of mammals in history. During the era, there were two interesting mammalian families that existed at the same relative time: the Entelodontidae and the Amphicyonidae. There has been speculation that the fall of the Entelodontidae … [Read more…]
The San Francisco Volcanic Field (SFVF) is located in northern Arizona and contains more than 600 volcanoes, which range in age from Pliocene to Quaternary. Traditional K-Ar dating has been widely used to determine ages of volcanic units in the SFVF, but low potassium content and concerns about excess Ar pose challenges for dating young … [Read more…]
The timing and nature of the formation of the Himalayan Orogeny remains unclear (Donaldson et al., 2013). The original theory is that these mountains were formed during a continent-continent collision (Liou et al., 2005) but recent finding of coesite (evidence of ultrahigh pressures greater than ~26 kb) in some eclogites in the Himalayas indicates that … [Read more…]
The Western Gneiss Region (WGR), Norway, is an ultrahigh-pressure (UHP) terrane containing coesite. Coesite forms at >29 kbar and >700oC indicating the WGR, which consists of Baltica basement and the overlying Lower, Middle, Upper, and Uppermost allochthons, was subducted to depths of ~125 km or greater (Smith, 1984). Zircon U–Pb ages from the different units … [Read more…]
The Western Gneiss Region (WGR) is one of the largest known areas in the world with well exposed ultrahigh-pressure (UHP) domains (including rocks that have been subducted >150 km deep); it is compiled of the Caledonian allochthons overlying Proterozoic Baltica basement (Roberts, 2003). The ultrahigh-pressure event, recorded in basement and allochthons, was Scandian in age … [Read more…]
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.
Lots of research has been conducted on Australia’s late glacial (30,000-20,000 years ago), deglacial (20,000-10,000 years ago), and Holocene (the last 10,000 years) climate; however, few climate reconstructions exist for northwestern Australia due to a lack of data. Drivers of climate variability over these time periods are important to understand because local climate adjusts to … [Read more…]
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.
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).
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.
The last several hundred thousand years have witnessed dramatic changes in sea level due to the growth and decay of the Greenland, Antarctic, and now-melted North American continental ice sheets. The last time sea level exceeded modern day levels was 120,000 years ago, at which time it was as much as 6-8 m above present. … [Read more…]
Mud layers trapped within stalagmites from caves in a variety of environmental settings have been interpreted as flood deposits. Here we present a combined petrographic and isotopic analysis of one glacial-age stalagmite, AUS-118 from Cape Range, coastal Western Australia. Stalagmite AUS-118 was thin sectioned and visually inspected and 121 mud layers were identified. The distance … [Read more…]
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…]
Tropical cyclones (a.k.a. hurricanes and typhoons) are among the most devastating forms of extreme weather events in terms of loss of life and destruction of property. Identifying long-term trends in tropical cyclone activity is crucial to understanding the mechanisms that drive variability in frequency and intensity. Historical records of cyclone activity are high-resolution, but short-reaching, … [Read more…]
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.
An ultrahigh-pressure (UHP) metamorphic zone has been identified in the North Qaidam Mountains of China. Located on the northeastern edge of the Tibetan Plateau, the North Qaidam Mountains contain UHP eclogites, which indicate subduction of continental materials to > 90 km deep.
The northeastern region of the Tibetan plateau is composed of multiple terranes and tectonically altered zones, including the North Qaidam (ultra)high-pressure metamorphic belt (NQMB). The NQMB is roughly 15 km wide, extends 350 km NW-SE, and contains well-exposed continental collision-type (ultra)high-pressure metamorphic rocks. Eclogites in the NQMB occur as blocks, boudins or layers within the … [Read more…]
Approximately one third of the global population lives in the area affected by the Indo-Australian monsoon. Understanding the variability and dynamics of Australian monsoon rainfall, especially in response to global climate change, is of critical importance. Research in Borneo and Indonesia has demonstrated that the strength of the Indo-Australian monsoon is tied to millennial-scale climate … [Read more…]
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.
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…]
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.
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…]
Few paleoclimate records preserve high-resolution information for the middle Holocene in (near) coastal Portugal, but this region contains many caves within a few kilometers of the coast. In addition, shells of shallow marine invertebrates record sea surface conditions and some of these were harvested and preserved in archaeological middens.
The North Qaidam Mountains on the northeastern edge of the Tibetan Plateau show evidence of ultrahigh-pressure (UHP) metamorphism, indicating subduction and exhumation of continental materials to > 90 km deep, within the mantle. The area most likely represents a suture zone, as an ophiolite is present, indicating the closing of an ocean. This ocean was … [Read more…]