Encyclopedia of the Great Plains

Share this article Share ‘It was such a big quake that everyone was scared,’ said a woman who answered the phone at a kindergarten hours later and declined to give her name. Rescuers used dynamite to clear boulders that had fallen across roads to reach Longmen and other damaged areas lying farther up the mountain valleys, state media reported. The quake – measured by the earthquake administration at magnitude Geological Survey at 6. People in their underwear and wrapped in blankets ran into the streets of Ya’an and even the provincial capital of Chengdu, 70 miles east of Lushan, according to photos, video and accounts posted online. The quake’s shallow depth, less than 8 miles, is likely to have magnified its impact. Chengdu’s airport shut down for about an hour before reopening, though many flights were cancelled or delayed, and its railway station halted dozens of scheduled train rides Saturday, state media said.

Indicators, from radiometric dating, of a young Earth

Share 50 shares But ‘questions have been raised regarding the suitability of these materials,’ researchers from Arizona State University said in a recent paper, in the journal Icarus. This means scientists are reluctant to crush them to study their contents and behaviour, so use rocks on Earth to test models instead. But a team of researchers from Arizona State University wanted to find out how meteorites compare with terrestrial rocks, to decide whether we can trust Earth rocks in tests.

The scientists found the cubes were almost as brittle as concrete.

The spherical Moeraki Boulders on New Zealand’s Koekohe Beach measure up to three metres in diameter and were formed from ancient marine mud on the sea floor that was compressed.

Using cosmogenic nuclides in glacial geology Sampling strategies cosmogenic nuclide dating Difficulties in cosmogenic nuclide dating Calculating an exposure age Further Reading References Comments How can we date rocks? Geologists taking rock samples in Antarctica for cosmogenic nuclide dating. They use a hammer and chisel to sample the upper few centimetres of the rock. Cosmogenic nuclide dating can be used to determine rates of ice-sheet thinning and recession, the ages of moraines, and the age of glacially eroded bedrock surfaces.

It is an excellent way of directly dating glaciated regions. It is particularly useful in Antarctica[1], because of a number of factors[2]: The lack of terrestrial marine organisms makes radiocarbon dating difficult; High winds make burial by snow less likely; Burial and cover by vegetation is unlikely. Cosmogenic nuclide dating is effective over short to long timescales 1, , , years , depending on which isotope you are dating.

Rocks

May 30, , University at Buffalo Infographic showing study sites. The conventional story says that the earliest settlers came via Siberia, crossing the now-defunct Bering land bridge on foot and trekking through Canada when an ice-free corridor opened up between massive ice sheets toward the end of the last ice age. But with recent archaeological evidence casting doubt on this thinking, scientists are seeking new explanations.

One dominant, new theory:

Significant Rock Features Australia has some of the oldest geological features in the world with the oldest known rocks dating from more than million years ago and rare zircon crystals dating back million years located in much younger rocks.

Landforms from Space Significant Rock Features Australia has some of the oldest geological features in the world with the oldest known rocks dating from more than million years ago and rare zircon crystals dating back million years located in much younger rocks. The zircons evolved very soon after the planet was formed. These ancient features compare with the oldest known rock on Earth in northwestern Canada. Scientists say that rock was formed million years ago. Some areas of Victoria and Queensland are geologically much younger as a result of volcanic activity which last erupted a few thousand years ago.

Australia’s youngest mainland volcano is Mount Gambier in South Australia which last erupted only about years ago. In recent years, the advent of improved technology and more extensive geological exploration has resulted in a greater knowledge of the age of rocks in Australia. It has resulted also in an increased ability to better understand the continent’s past. This has been achieved by combining exploration methods such as deep seismic surveys with geochronology methods, including use of equipment such as the Sensitive High-Resolution Ion Microprobe, or SHRIMP.

This equipment uses uranium and lead isotopes from tiny portions of zircon crystals which have been extracted from rock samples to calculate the age of the crystal based on the natural decay rate of uranium to lead.

NASA

A sedimentary rock is just what it sounds like: Sedimentary rocks can consist of sand, clay, chalk and fossils and as a marine geologist I find sedimentary rocks very fascinating! Some may think that sedimentary rocks is a bit dull since sedimentary rocks isn’t created by violent and exciting volcano eruptions from the Earths mantle like the igneous rocks. No, sedimentary rocks have another type of fascinating origin and every single rock tells a story if you just know how to “read” the rock!

That is one of the fascinating thing with sedimentary rocks!

10 Be dating of boulders on moraines from the last glacial period in the Nyainqentanglha mountains, Tibet.

What species were they? Continue reading the main story Photo A boulder discovered at the Cerutti Mastodon site thought to have been used by early humans as a hammerstone. Grayson, an archaeologist at the University of Washington, who faulted the new study for failing to rule out more mundane explanations for markings on the bones.

In , construction workers dug up the mastodon bones while clearing earth to build a sound barrier along Route 54 in San Diego County. A team of paleontologists from the museum spent the next five months excavating the layer of sediment in which they were found. The team discovered more scattered bone fragments, all of which seemed to have come from a single mastodon.

From the start, the remains seemed unusual. The thick bones were broken and smashed, and near the animal were five large rounded stones. In an effort to reproduce the markings, the researchers used similar rocks to break apart fresh elephant bones in Tanzania.

Geology with Terry J. Boroughs: Geologic Dating Lab.

View larger Rock art in the Great Plains consists of both petroglyphs markings that have been pecked, scratched, incised, or abraded on natural rock surfaces and pictographs painting on nonportable rock surfaces. Petroforms sometimes called geomorphs, in which large stones or boulders have been used to outline anthropomorphic, zoomorphic, or geometric forms are found primarily in the northeastern U.

Plains and southern Saskatchewan. Rock art was noted in the journals of European American explorers, but it was not until the s that petroglyphs and pictographs were thoroughly documented and interpreted for professional publication.

In this study we used two independent surface-exposure dating techniques – rock-varnish microlamination and cosmogenic 36Cl dating methodologies – to estimate minimum- and maximum-limiting ages, respectively, of the precarious boulders and by inference the elapsed time since the sites were shaken down.

Geological Time and the Rock Record The rock record of interest to students of Geology is dominantly the record of sedimentary rocks. Igneous rocks include volcanic rocks, which can and do cover large areas of Earth’s surface. But they do not in general have many fossils in them. Occasionally a lava flow may overwhelm and preserve organisms as fossils, but that is rare. Volcanic ash beds are important in dating other rock layers, however, as we shall see.

Sedimentary rocks are laid down and accumulated on the surface of the earth under normal temperatures and pressures. The particles that make up the sediments – clays, silts, sand, pebbles, and boulders, are formed from pre-existing rocks by weathering and are then transported by various agents of erosion until they are finally deposited in a permanent resting place. Molded then by further sedimentary layers deposited on top of them, sediments are compressed, so that any water that lies between the grains is squeezed out in dewatering, often leaving behind any minerals it contained in solution to form cements that bind the sediments together.

Eventually the squeezing and cementation allows one to say that a rock has formed from the original sediment. The process is called lithification. If in the process, organisms or traces of organisms have been buried along with the sedimentary particles, then those organisms may survive well enough to be exposed, recognized, and collected as fossils. We will return to the process of fossilization.

We need to be able to place any fossils we find in the context of the rocks we find them in.

The Grand Canyon and the Age of the Earth

Or perhaps the mysterious Stonehenge, made of bluestone and dating back to possibly B. In this case, the bluestone is actually dolerite that has been cracked or split by frost. For the sake of this purpose however, we focus on the symbolism of the material, which, in essence, is rock. It stands to reason then, that we utilize rock now to commemorate important events in our own lives and era.

Today, it is common to use boulder style rocks to commemorate special events, such as the opening of a park, a dedication to a special person or event, or even as a tribute to the passing of a loved one.

Scientists then applied this dating technique to inorganic materials like rocks. They were able to measure the decay of various isotopes like uranium- and thorium in rocks .

Ocean Sciences News Mysterious Boulders Suggest Ancient Foot-Tall Tsunami The suspected sudden collapse of a nearby volcano’s flank may have triggered an enormous wave that carried large boulders high onto Santiago Island in Cape Verde, a new study finds. A member of a research team hammers the surface of a huge rock on Santiago Island, which lies off the west coast of Africa.

The team published new evidence today that an enormous tsunami may have carried this and many other hefty boulders high up onto the island. Ricardo Ramalho By JoAnna Wendel 2 October What kind of force could lift almost 50 van-sized boulders and hurl them meters feet above sea level onto a volcanic plateau? This question puzzled geophysicist Ricardo Ramalho since , when he first came across the mysterious boulders on Santiago Island—a small Atlantic island almost kilometers due west of Senegal.

After dating the boulders, Ramalho realized there was only one event in the area that was possibly capable of triggering such a towering wave—the Fogo volcano flank collapse , where cubic kilometers 40 cubic miles of rock from the nearby volcano slid off into the ocean. If that collapse, or part of it, had taken place suddenly, the mountain of rock hitting the sea could have triggered a tsunami meters feet high, Ramalho and his colleagues report—roughly 8 times higher than the greatest peak of the Sumatra tsunami that killed more than , people.

He and his team published the research today in Science Advances. Pico du Fogo is the new volcano that grew after the flank of the original volcano collapsed sometime between 65 and thousand years ago. Ricardo Ramalho By studying the tsunami deposits around the Fogo volcano—which is one of the largest and most active volcanoes in the world—previous scientists had dated the collapse to sometime between 65 and thousand years ago.

Large Rocks and Boulders

Photo copyright Sara J. Bruegel, From far away, the two short stacks of rocks, sitting precariously on top of the mountain, looked like they had been put there by someone. No way could a person stack them. The next day, we hiked to place where massive boulders were piled at the base of a mountain.

Precariously balanced boulders that could be knocked down by strong earthquake ground motion are found in some seismically active areas of southern California and Nevada In this study we used two independent surface-exposure dating techniques-rock-varnish microlamination and cosmogenic (CI)-C dating methodologies-to estimate minimum-and maximum-limiting ages, respectively, of the .

A wiry woman, impressively dressed in a broad-brimmed leather hat and a buckskin vest as if she were still ready for sixties counter-culture happenings, she spoke in a precise, possibly Germanic accent. Striated basalt amid the woods This was Rita Schaad, co-owner with her husband Felix of the farmland where we were about to tour the Wairere Boulders, close by Hokianga Harbour near the top of the North Island peninsula. Her obvious passion for the place kept her happily talking to us, a willing and bemused audience, for the next fifteen minutes.

We had come with little information about the boulders, though they were mentioned in our NZ guidebook and were highlighted on our Jasons map of the area — a result, Rita admitted, of paid advertising. And apparently the Schaads had little information about the boulders when they originally acquired the property. A pool in the forest along the Wairere waterway That move was about thirty years ago, when they left their native Switzerland to find a place farther apart from the madding crowd.

The acreage they bought offered plenty of farming land and its own water source, which eased down the volcanic hills through diverse rainforest. But the waterway was somewhat unusual, because it but was filled with massive rocks heaped helter-skelter as if tossed by some giant from afar. They constitute what remains of a basalt layer, a dense heavy rock that looked to us like a darker form of granite.

Dating precariously balanced rocks in seismically active parts of California and

Public Domain Constructing an Obelisk Although the ancient Egyptians recorded a great deal about the meaning of obelisks, they left us little about the process by which obelisks were made. The conventional explanation is that the ancient Egyptians chiseled into granite blocks with copper tools and then inserted wooden wedges which were soaked with water. As the wooden wedges were soaked they expanded – causing the granite to split apart.

The rocks of Castle Hill Nestled among the eastern ranges of the Southern Alps, an hour’s drive from Christchurch, lies a gentle basin bulging with huge boul­ders and rock outcrops.

Building good looking stone walls A method even beginners can tackle sucessfully to build rock walls, using concrete foundations, mortar, and formwork. Before I start describing this method, I would like to dispose of some hopelessly romantic and ill-founded notions about dry stone walls. Certainly, dry stone walls are quick and easy to construct, though they soak up a staggering amount of rock for their height and utility.

Constructed properly which in Australia they rarely are, it is a skilled craft they are a beautiful thing. But they are never maintenance free. There is a wonderful poem, Mending Wall by Robert Frost which begins: Mending Wall Something there is that doesn’t love a wall, That sends the frozen-ground-swell under it And spills the upper boulder in the sun, And make gaps even two can pass abreast.

Dark Roasted Blend: Sensational Rock Formations: Moeraki Boulders

Data from stream sediment geochemical surveys document that South Greenland is enriched in a range of these elements relative to the rest of Greenland and to estimates of the upper crust composition. Distribution patterns for individual elements within south Greenland exhibit enriched regions that are spatially related to lithological units, crustal structure and known mineralisation.

The Northern Domain of South Greenland includes the southernmost part of the orthogneiss-dominated North Atlantic craton. Orogenic gold mineralisation is hosted by quartz veins and hydrothermally altered rocks associated with shear zones intersecting the Mesoarchaean Tartoq Group of mafic metavolcanic rocks. Geochemical exploration indicates that additional potential for gold mineralisation exists within Palaeoproterozoic supracrustal rocks overlying the Archaean basement.

Four gneiss boulders on Holocene glaciofluvial fans offset by the Kongur normal fault in the Chinese Pamir Plateau were sampled to test the reliability and applicability of rock surface luminescence dating.

Tertiary rocks Major subdivisions of the Tertiary System Classically, the Cenozoic Era was divided into the Tertiary and Quaternary periods, separated at the boundary between the Pliocene and Pleistocene epochs formerly set at 1. In the International Commission on Stratigraphy ICS decided to recommend keeping the Tertiary and Quaternary periods as units in the geologic time scale but only as sub-eras within the Cenozoic Era.

Under this paradigm , the Paleogene and Neogene span the interval formerly occupied by the Tertiary. The Paleogene Period, the oldest of the three divisions, commences at the onset of the Cenozoic Era and includes the Paleocene Epoch 66 million to 56 million years ago , the Eocene Epoch 56 million to The Neogene spans the interval between the beginning of the Miocene Epoch 23 million to 5.

The Quaternary Period begins at the base of the Pleistocene Epoch 2. Paleogene Period in geologic timeThe Paleogene Period and its subdivisions. International Commission on Stratigraphy ICS Precise stratigraphic positions for the boundaries of the various traditional Tertiary series were not specified by early workers in the 19th century. It is only in more recent times that the international geologic community has formulated a philosophical framework for stratigraphy.

By specifying the lower limits of rock units deposited during successive increments of geologic time at designated points in the rock record called stratotypes , geologists have established a series of calibration points, called Global Boundary Stratotype Sections and Points GSSPs , at which time and rock coincide. These boundary stratotypes are the linchpins of global chronostratigraphic units—essentially, the points of reference that mark time within the rock—and serve as the point of departure for global correlation.

Several boundary stratotypes have been identified within Tertiary rocks. Increasingly, this boundary is known as the Cretaceous-Paleogene, or K-P, boundary. Its estimated age is 66 million years.

localhost:81 #18 – Absolute radiometric age dating of rocks and geologic materials