ORDOVICIAN PERIOD The Ordovician Period is the second period of the Paleozoic Era and began 485.4 million years ago and ended 443.4 million years ago (when the Silurian Period began). Four continents were present and separated by three main oceans. Laurentia was composed of present-day North America, part of Scotland, and Greenland and was near the equator. Siberia-Kazakhstan was east of Laurentia, slightly north of the equator. The Iapetus Ocean separated these two masses on the south from the
probably think horseshoe crabs are crustaceans, but you’d be wrong. They actually aren’t crabs at all, and there’s more about the horseshoe crab that you wouldn’t believe. This weird-looking marine animal survived two mass extinctions and lived in the Ordovician Period. To begin with, the horseshoe crab, one the world’s oldest living creatures, are quite active. This fascinating crab has ten small walking legs under a strong, sturdy exoskeleton, a long spine in the abdomen, and a long pointy tail
Introduction: The Lophophore is a characteristic feeding organ possessed by four major groups of animals: the Brachiopod, Bryozoan, Entoprocts, and Phoronida, which collectively constituted the Lophophorata. [1] All Lophophore are found in aquatic organisms The Lophophore can most easily be described as a ring of tentacles, but is often horseshoe-shaped or coiled. Why do we call the tentacles a Lophophore? Because the tentacles have several distinctive characteristics that differentiate them from
rare occurrence of events proceeded the Triassic geologic periods and the Paleozoic and Mesozoic eras. This mass disaster was the largest dissipation of living life on planet earth; it is believed to be even superior to other crises such as the Ordovician and Devonian events and the conclusion of the cretaceous era that came upon the dinosaurs. The eradication of species numbers average at a toll close to one hundred percent of earths total living creatures. “It is the Earth's most severe known extinction
fossils and relative dating are the proof of the creatures that inhabited the Earth during this period. Even though there was an explosion of marine life, sixty percent of the species became extinct due to climatic changes and glaciation. After the Ordovician period is the Silurian period (440-410mya), which is best known for life on land. Once the climate stabilized, land plants grew near the equator and the evolution of fishes began. The first known freshwater fish, and fish with jaws appears. The
470 million years, from Ordovician sandstones to Pleistocene glacial till. The Ordovician St. Peter Formation sandstone was deposited across the midcontinent during the second major marine transgression of the Paleozoic Era. The first transgression deposited Upper Cambrian to Lower Ordovician clastics and carbonates. The clastic to carbonate rock transition is consistent with gradual sea level rise over the North American craton. Sea level dropped late in the early Ordovician, exposing the carbonate
VI. Cambrian When the Cambrian started, there was an epicontinental sea that covered the Southeastern portion of what is today Minnesota (Ojakangas and Matsch 1982). Streams were flowing into the sea off the land in western and northern Minnesota carrying sand to the seashore. This is why there was a lot of sandstone deposited during the Cambrian. Figure 11 shows a strat column for the Cambrian rocks found in Minnesota. The sand that was deposited came from the erosion of the igneous and metamorphic
Despite being only twenty-five miles apart, Mystery Cave and Niagara Cave are surprisingly different. One of the major differences between Niagara and Mystery Cave is that Mystery Cave has bats. Another difference is Mystery Cave is owned by the State of Minnesota, while Niagara Cave is privately owned. On the other hand, since the caves are located in southeastern Minnesota, they both are made of limestone, and ancient fossils are found in each of the caves. Mystery Cave is the only cave in Minnesota
A mass extinction or extinction event is the phenomenon in which many species of life on Earth become extinct in a relatively short period of time. Mass extinction refers to an extinction affecting a great many different groups of organisms occupying diverse and wide-spread environments. Extinction of species has occurred throughout the history of life on Earth, but mass extinctions are those events that greatly exceed the normal or background extinction rate. Can mass extinction be inevitable? There
Introduction Evolving Planet exhibit at the Field Museum of Natural History is a great exhibit that describes the origin of our planet Earth through the evolution theory. This exhibit provides animated and hands-on features to support this theory that our planet originated around 4.5 billion years ago and the history of our planet expanding across several eras and periods attributing to the existence of evolution. Evolving Planet is a vibrant, fun and comprehensive experience with the mission to
A Look into the Past Depositional conditions and structural deformation The Austin Glen formation, which may be found at the Johnson Iorio Memorial Park, encompasses an abundance of clastic sedimentary rocks. More specifically, thin black shale and thick greywacke compose this formation. The thin black shale may be described as fine-grained and its color derives from lack of oxidation. This indicates the rock formed in deep ocean conditions. The shale layers are thin, and are approximately
Precambrian Geologic The Precambrian era is about 90% of the earth’s geologic life. It refers to all geologic time before 600 million years ago. During the Precambrian era, the earth formed along with the oceans and atmosphere. Originally, the earth was in a molten state, but as it cooled down, it developed a hard crust and oceans that developed water vapor to form an atmosphere. About five hundred million years after the earth was formed, small continents started to form. The plate tectonics also
life. 4. The Paleozoic era began with the Cambrian period, around 540 million years ago. At this time, marine life became very abundant, and the first fish started to appear. Animal families became more diverse 480 million years ago, starting the Ordovician period, which ended
I. INTRODUCTION A significant portion of New England was formed as a result of an accretionary orogen. Southeastern New England is marked by a series of terranes that accreted onto the Laurentian supercontinent during the Silurian and Devonian. The Terranes of Gander, Nashoba, Avalon, and Meguma are present from west to east in eastern Massachusetts and all of are Gondwanan provenance. Their modern-day juxtaposition suggests that the marginal Gondwanan micro-continents collided sequentially from
1. Give a brief overview of the evolution of fish. Fish were amongst the first known chordates about 500 million years ago. Therefore, they have a very elaborate and complicated evolutionary history. The first type of fish to appear during the Ordovician era were called Ostracoderms. They had their head and flanks covered with a bony armor while they had a cartilaginous back. The shield was used to keep off predators. The extinction of the Ostracoderms during the Devonian period saw the emergence
area had a passive fault, similar to the east coast of the United States today. The mud and silt from the ocean settled in the Yosemite area and eventually became shale, siltstone, and carbonate rocks (United States of America). By the end of the Ordovician Period, the fault changed from a passive to an active fault. The oceanic plate started to subduct under the continental crust and push the shale upward, forming the first mountains in the western United States. At first, these were volcanic islands
On Sunday September 20th The class of Geog 2020 went on a field trip to observe bio-physical features of the Ottawa area. Our first stop was to Erskine Johnson Elementary School in Kanata where there is a large visible outcrop of precambrian rock in the school yard. Our next stop was to The March Highlands Conservation Forest, a forested area that features beaver ponds and sand stone beddings. Next we moved on to the Crozier pit, a mining sight near Renfrew that features a large precambrian marble
Abstract. This report covers three field trips have been done for the course of “Geology of Nova Scotia”. Nova Scotia is a province located in Eastern Canada fronting the Atlantic Ocean. The geological history of the province spans more than 1.2 billion years . Nova Scotia has a great variety of coastal landforms. Most of the land in this province is bedrock. As the result, erosion and transportation of unconsolidated material, have been doing formed beautiful landforms like beaches and marshes.
The Ordovician actually saw greater amounts of origination, but the Devonian has been assigned more biozones than the former (Boardman, 1983). Also interesting about the conodonts origination rates is that the rates were only higher that extinction rates for
bodies and many legs that were positioned under a heavily calcified, segmented shell. They first appeared in the Early Cambrian Period (544 million years ago) and thrived through the Middle and Late Cambrian times before their extinction in the Ordovician period (495 million years ago). In their 49 million year existence, they diversified quickly and produced a fossil record that geologists refer to often. Arthropods are a phylum of hard-shelled creatures with multiple body segments and jointed