Processes That Shape the Earth (Physics in Action)
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As a result, the rocks begin to change. Rocks that have changed below Earth's surface due to exposure to heat , pressure, and hot fluids are called metamorphic rocks.
River processes
Geologists often refer to metamorphic rocks as "cooked" because they change in much the same way that cake batter changes into a cake when heat is added. Cake batter and cake contain the same ingredients, but they have very different textures, just like sandstone, a sedimentary rock, and quartzite, its metamorphic equivalent. In sandstone, individual sand grains are easily visible and often can even be rubbed off; in quartzite, the edges of the sand grains are no longer visible, and it is a difficult rock to break with a hammer, much less rubbing pieces off with your hands.
Some of the processes within the rock cycle, like volcanic eruptions, happen very rapidly, while others happen very slowly, like the uplift of mountain ranges and weathering of igneous rocks. Importantly, there are multiple pathways through the rock cycle. Any kind of rock can be uplifted and exposed to weathering and erosion ; any kind of rock can be buried and metamorphosed. As Hutton correctly theorized, these processes have been occurring for millions and billions of years to create the Earth as we see it: The rock cycle is not just theoretical; we can see all of these processes occurring at many different locations and at many different scales all over the world.
As an example, the Cascade Range in North America illustrates many aspects of the rock cycle within a relatively small area, as shown in Figure 6. The Cascade Range in the northwestern United States is located near a convergent plate boundary , where the Juan de Fuca plate, which consists mostly of basalt saturated with ocean water is being subducted, or pulled underneath, the North American plate. As the plate descends deeper into the Earth, heat and pressure increase and the basalt is metamorphosed into a very dense rock called eclogite.
All of the ocean water that had been contained within the basalt is released into the overlying rocks, but it is no longer cold ocean water. It too has been heated and contains high concentrations of dissolved minerals , making it highly reactive, or volatile. These volatile fluids lower the melting temperature of the rocks, causing magma to form below the surface of the North American plate near the plate boundary.
Some of that magma erupts out of volcanoes like Mt.
When that lava cools, it hardens into new rock. Actual greenhouses use glass to trap heat. Weathering and erosion take millions of years to have an effect on the Earth, but those effects can be dramatic. Destructive forces break down land. Oftentimes, volcanoes are the result of pieces of the Earth's crust moving around, but hot spots , formed by mantle plumes in the Earth's interior, push through the crust creating a volcanic zone.
Helens, cooling to form a rock called andesite , and some cools beneath the surface, forming a similar rock called diorite. Storms coming off of the Pacific Ocean cause heavy rainfall in the Cascades, weathering and eroding the andesite. Small streams carry the weathered pieces of the andesite to large rivers like the Columbia and eventually to the Pacific Ocean, where the sediments are deposited. Continual deposition of sediments near the deep oceanic trench results in the formation of sedimentary rocks like sandstone. Eventually, some sandstone is carried down into the subduction zone, and the cycle begins again see the Experiment!
The rock cycle is inextricably linked not only to plate tectonics, but to other Earth cycles as well. Weathering , erosion , deposition, and cementation of sediments all require the presence of water, which moves in and out of contact with rocks through the hydrologic cycle; thus weathering happens much more slowly in a dry climate like the desert southwest than in the rainforest see our module The Hydrologic Cycle for more information.
The uplift of mountain ranges dramatically affects global and local climate by blocking prevailing winds and inducing precipitation. The interactions between all of these cycles produce the wide variety of dynamic landscapes we see around the globe.
Some processes that shape the Earth happen quickly; others take millions of years. This module describes the rock cycle, including the historical development of the concept. The relationship between uniformitarianism, the rock cycle, and plate tectonics is explored in general and through the specific example of the Cascade Range in the Pacific Northwest. The rock cycle is the set of processes by which Earth materials change from one form to another over time. The concept of uniformitarianism, which says that the same Earth processes at work today have occurred throughout geologic time, helped develop the idea of the rock cycle in the s.
Bookmark Glossary Terms We all see changes in the landscape around us, but your view of how fast things change is probably determined by where you live. Although they had lived in all levels of the ocean, after dying, their remains ended in the same place: But a number of the seafloor cores contained a layer that was different.
Deposited some 56 million years ago, this layer covered a period of just 5, to 10, years. It contained almost no fossils, just a layer of barren clay.
CurioCity - CurioCité | The processes that shape landforms
That clay is made up of sediments that washed into the ocean from distant coastlines. The scientists were surprised to see that clay. Most layers in these cores contain so many foraminifera shells that any minuscule grains of clay are barely visible. So only the clay survived. During this period, the acidic water had turned their shells to goo.
Such deep ocean waters were simply too acidic for many bottom-dwellers to survive, Thomas explains. As many as half of all bottom-dwelling foraminifera species went extinct during that period. Although 5, to 10, years sounds like a long time and it is on a human timescale , it is a brief moment in geologic time. This extinction event is so clearly visible in the rock record that scientists use it to mark the end of the Paleocene Epoch, Some experts now fear similar evidence is accumulating in the seafloor sediment that will one day turn into a rock record of our time.
This allowed time for surface waters to circulate. Much of the carbonic acid eventually moved into deeper waters, where it killed off those bottom-dwellers. Those activities have helped cause CO 2 levels in the atmosphere to skyrocket over a span of just a couple of hundred years. Compare that to the thousands of years it took 56 million years ago. The loss of surface formanifera may then ripple throughout the whole marine food web. Not all scientists agree on whether to officially declare our current geologic period the Anthropocene.
One who has concerns about doing so: Finney heads the International Commission of Stratigraphy. Stratigraphy is the study of rock layers. And his organization is responsible for setting the geologic time scale. But plants have had a far greater impact, he argues. Plants, and the oxygen they generate, changed the land, the air and the water. In everyday speech, it communicates the impact people are having on our planet. When carbon dioxide dissolves in water, it triggers chemical reactions that create carbonic acid.
Uniformitarianism
On a wheel, the axis would go straight through the center and stick out on either side. These dwell nearly everywhere on Earth, from the bottom of the sea to inside animals. A scientist who studies such interactions is called a biogeochemist. This colorless, odorless gas also is released when organic matter including fossil fuels like oil or gas is burned.
Plants convert carbon dioxide into oxygen during photosynthesis, the process they use to make their own food. Its scientific symbol is CO 2. When fired under intense heat, clay can become hard and brittle. Cores allow scientists to examine layers of sediment, dissolved chemicals, rock and fossils to see how the environment at one location changed through hundreds to thousands of years or more.
Examples include tropical reefs, rainforests, alpine meadows and polar tundra. Erosion can be exceptionally fast or exceedingly slow.
Water is a major factor in the processes that shape Earth's surface. . motion. The mobile rock beneath the rigid, but fragile plates that make up Earth's .. physics. She went on to complete a master's degree in physics at Princeton University in. Coverage includes energy, the central concept of physics, forces and motion, the nature of matter, planets, stars and galaxies, processes that shape the earth.
Causes of erosion include wind, water including rainfall and floods , the scouring action of glaciers, and the repeated cycles of freezing and thawing that often occur in some areas of the world. These changes usually result in a new type of organism better suited for its environment than the earlier type. Member organisms depend on others within this network as a source of food. They make up the base of the marine food web.
There are many different types of fossils: Scientists divide geologic time into successively briefer intervals of time, called eons, periods, epochs, eras and ages. People who work in this field are known as geologists. Planetary geology is the science of studying the same things about other planets.
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During that time, which can last hundreds to thousands of years, glaciers and ice sheets expand in size and depth. The most recent ice age peaked 21, years ago, but continued until about 13, years ago. Our planet has experienced 5 known mass extinctions. It takes a microscope to view such tiny objects, such as bacteria or other one-celled organisms. Most rocks contain several different minerals mish-mashed together.
A mineral usually is solid and stable at room temperatures and has a specific formula, or recipe with atoms occurring in certain proportions and a specific crystalline structure meaning that its atoms are organized in certain regular three-dimensional patterns. Initially established in under another name The Survey of the Coast , this agency focuses on understanding and preserving ocean resources, including fisheries, protecting marine mammals from seals to whales , studying the seafloor and probing the upper atmosphere.
Coastal processes
Scientists who work in this field are called paleoceanographers. Some, like algae, may appear plant-like. Those known as protozoans may appear animal-like. And still others appear fungi-like. Unlike lakes and streams, seawater — or ocean water — is salty. The stratosphere stretches from 10 kilometers to 50 kilometers about 6. Another example of a slow constructive force is the deposition of sediment at the mouth of a river. Water carries sediment down river and as the river becomes more shallow, the sediment is deposited, forming landforms such as deltas.
Mountains are also an example of a slow constructive force due to two tectonic plates being pushed into each other. Some changes to the Earth take place in a matter of seconds instead of millions of years. The main quick constructive force is a volcano. A volcano that erupts violently can send lava and ash shooting out within seconds. When that lava cools, it hardens into new rock. Destructive forces break down land. The two main forces that break down land slowly are weathering and erosion.
Weathering is the breaking down of rocks due to forces such as wind and water. The pieces of rock are then moved elsewhere through the process of erosion.