Geology, Earth Resources and Climate Change (copy)

Earth

• A dynamic planet and constantly changing structure

• A layered sphere.

Core

• Composed of a dense, intensely hot mass of metal, mostly iron.

• Thousands of Kilometers in diameter

• Solid in center but more fluid in the outer core

• Generates the magnetic field that envelopes the earth

Mantle

• Surrounding the molten outer core

• Hot, pliable layer of rock

• Much less dense than the core because it contains a high concentration of lighter elements, such as oxygen, silicon and magnesium.

Crust 

• Cool, lightweight, brittle rock, outermost layer of the earth

• Crust below oceans is relatively thin (8-15km), is dense, and young (less than 200 million years old) because of constant recycling

• crust under continents is relatively thick (25-75km) and light, and as old as 3.8 billion years, with new material being added continually. It also is predominantly granitic, while oceanic crust is mainly dense basaltic rock.

Antonio Snider

In 1855, he published a sketch showing how the two continents could fit together, jigsaw-puzzle fashion, which suggests that perhaps these continents had once been part of the same landmass, which had later broken up.

Alfred Wegener

• He was struck not only by the matching coastlines but by geologic evidence from the continents.

• He proposed that all continental landmasses had once formed a single supercontinent “Pangea“ Greek for “all lands”, which had then split apart, the modern continents moving to their present positions via process called continental drift.

Tectonics

Is the study of large scale movement and deformation of the earths outer layers.

Plate Tectonics

Relates such deformation to the existence and movement of rigid plates over a weaker, more plastic layer in the earths upper mantle.

Lithosphere

• The earth’s crust and uppermost mantle that are somewhat brittle and elastic. Together they make up the outer solid layer of the earth called ______.

• From the Greek Word “Lithos” meaning Rock.

• Thinnest underneath the oceans, where it extends to a depth of about 50km.

Asthenosphere

• The layer below the Lithosphere

• From the Greek Word “asthenes” meaning without strength.

• Its presence makes the concept of continental drift more plausible.

• Its lack of strength or rigidity results from a combination of high temperatures and moderate confining pressures that allows the rock to flow plastically under stress.

Divergent Plate Boundaries

• Lithospheric plates Moves Apart

• The pulling-apart of the plates of lithosphere results in earthquakes along these boundaries

• Continents can be rifted apart, and most ocean basins are believed to have originated through continental rifting.

Seafloor Spreading Ridges

Most common type of divergent boundary worldwide, and it is already noted the formation of new oceanic lithosphere at these ridges.

Convergent Plate Boundaries

• Plates Moving Toward Each Other.

• What happens depends on what sort of lithosphere is at the leading edge of each plate; one may have ocean-ocean, ocean-continent or continent-continent convergence

• This type of plate boundary, where one plate is carried down below (subducted beneath) another, is called a subduction zone.

Transform Boundaries

• As the plates scrape past each other, earthquakes occur along the transform fault. Transform faults may also occur between a trench (subduction zone) and a spreading ridge, or between two trenches, but these are less common.

• The offset is a special kind of fault, or break in the lithosphere, known as a transform fault.

• The famous San Andreas Fault in California is an example of a transform fault.

Mineral

• A naturally occurring, inorganic, solid element or compound with a definite chemical composition and a regular internal crystal structure

• No two minerals are identical in both respects, though they may be the same in one.

• A mineral’s composition and crystal structure can usually be determined only by using sophisticated laboratory equipment.

Silicates

• Two most common elements in the earth’s crust are silicon and oxygen. 

• Is the largest compositional group of minerals, all of which are compounds containing silicon and oxygen, and most of which contain other elements as well.

• This group of minerals is so large that it is subdivided on the basis of crystal structure, by the ways in which the silicon and oxygen atoms are linked together.

Quarts

• The best known silicate

• Simplest, containing only silicon and oxygen

• A framework silicate, with silica tetraheda linked in three dimensions, which helps make it relatively hard and weathering-resistant

• Found in variety of rocks and soil

• The most common use of pure quarts is in the manufacture of glass

Feldspars

• The most abundant group of minerals in the crust is a set of chemically similar minerals known as _________.

• Used in the manufacture of ceramics

Ferromagnesian

• Dark-colored (black, brown, or green) silicates that contain iron and/or magnesium, with or without additional elements

Olivine

Simple ferromagnesian mineral, is a major constituent of earth’s mantle; gem-quality olivines from mantle-derived volcanic rocks are the semiprecious gem peridot

Micas

• Group of several silicate minerals with similar physical properties, compositions, and crystal structures

• Are sheet silicates, built on an atomic scale of stacked-up sheets of linked silicon and oxygen atoms

• Because the bonds between sheets are relatively weak, the sheets can easily be broken apart. 

Clays

• Another family within the sheet silicates

• The sheets tend to slide past each other, a characteristic that contributes to the slippery feel of many clays and related minerals

• Somewhat unusual among the silicates in that their structures can absorb or lose water, depending on how wet conditions

• Used in making ceramics and in building materials

• Other clays are useful as lubricants in the muds used to cool the drill bits in oil-drilling rigs.

Nonsilicates

Mineral group is defined by some chemical constituent or characteristic that all members of the group have in common. Most often, the common component is the same negatively charged ion or group of atoms

Rocks

• Solid, cohesive aggregate of one or more minerals, or mineral materials.

• 3 broad categories of rocks are: Igneous, Sedimentary, Metamorphic

Igneous Rock

• A rock formed by the solidification and crystallization of a cooling magma.

• Igneous is derived from the Latin term ignis, meaning “fire.”

Plutonic Igneous Rock

• The name is derived from Pluto, the Greek god of the lower world. 

• Formation: If a magma remains well below the surface during cooling, it cools relatively slowly, insulated by overlying rock and soil. It may take hundreds of thousands of years or more to crystallize completely. Under these conditions, the crystals have ample time to form and to grow very large, and the rock eventually formed has mineral grains large enough to be seen individually with the naked eye

Lava

• A magma that flows out on the earth’s surface while still wholly or partly molten is called _____.

• Is a common product of volcanic eruptions, and the term volcanic is given to an igneous rock formed at or close to the earth’s surface.

Basalt

Is the most common volcanic rock. A dark rock in ferromagnesian minerals and feldspar.

Sediments

Are loose, unconsolidated accumulations of mineral or rock particles that have been transported by wind, water, or ice, or shifted under the influence of gravity, and redeposited.

Beach Sand

Is a kind of sediment; so is the mud on a river bottom

Soil

Is a mixture of mineral sediment and organic matter

Lithification

Is the set of processes by which sediments are transformed into rock. (from Greek word lithos, meaning “stone”)

Sedimentary Rocks

Are formed at or near the earth’s surface, at temperatures close to ordinary surface temperatures. They are subdivided into two groups—clastic and chemical.

Clastic Sedimentary Rocks

• From the Greek word klastos, meaning “broken”

• Formed from the products of the mechanical breakup of other rock

Sandstone

Is a rock composed of sand-sized sediment particles, 16 to 2 millimeters (0.002 to 0.08 inches) in diameter.

Shale

Is made up of finer-grained sediments, and the individual grains cannot be seen in the rock with the naked eye.

Conglomerate

Is a relatively coarse-grained rock, with fragments above 2 millimeters (0.08 inches) in diameter, and sometimes much larger.

Chemical Sedimentary Rocks

Form not from mechanical breakup and transport of fragments, but from crystals formed by precipitation or growth from solution.

Coal

Is derived from the remains of land plants that flourished and died in swamps.

Metamorphic Rocks

• The name metamorphic comes from the Greek for “changed form.” 

• One that has formed from another, preexisting rock that was subjected to heat and/or pressure.

Contact Metamorphism

Is when hot magma formed at depth rises to shallower levels in the crust, it heats the adjacent, cooler rocks, and they may be metamorphosed.

Quartzite

Is a quartz-rich metamorphic rock, often formed from a very quartz-rich sandstone.

Marble

Is metamorphosed limestone in which the individual calcite grains have recrystallized and become tightly interlocking.

Amphibolite

Can be used for any metamorphic rock rich in amphibole. It might have been derived from a sedimentary, metamorphic, or igneous rock of appropriate chemical composition; the presence of abundant metamorphic amphibole indicates moderately intense metamorphism, not the previous rock type.

Slate

Is metamorphosed shale that has developed foliation under stress.

Schist

Is a coarser-grained, mica-rich metamorphic rock in which the mica flakes are similarly oriented.

Economic Mineralogy

Is the study of resources that are valuable for manufacturing and are, therefore, an important part of domestic and international commerce

Metal Bearing Ores

Are minerals with unusually high concentrations of metals.

Metals

• The metals consumed in greatest quantity by world industry include iron (740 million metric tons annually), aluminum (40 million metric tons), manganese (22.4 million metric tons), copper and chromium (8 million metric tons each), and nickel (0.7 million metric tons). 

• Largest sources of metals are China, Australia, Russia, Canada, and the United States

Nonmetals

• Minerals are a broad class that covers resources from silicate minerals (gemstones, mica, talc, and asbestos) to sand, gravel, salts, limestone, and soils. 

• Durable, highly valuable, and easily portable, gemstones and precious metals have long been a way to store and transport wealth

High-purity silica sand

Is our source of glass. These materials usually are retrieved from surface pit mines and quarries, where they were deposited by glaciers, winds, or ancient oceans.

Open Pit Mines

Are used to extract massive beds of metal ores and other minerals.

Over Mountain Removal

A coal mining method mainly practiced in Appalachia. Long, sinuous ridge-tops are removed by giant mining machines to expose horizontal beds of coal.

Smelting

Or roasting ore to release metals—is a major source of air pollution. One of the most notorious examples of ecological devastation from smelting is a wasteland near Ducktown, Tennessee.

Heap Leach Extraction

Which is often used to get metals from low-grade ore, has a high potential for environmental contamination.

Earthquakes

Are sudden movements in the earth’s crust that occur along faults (planes of weakness) where one rock mass slides past another one, as was the case along the Enriquillo– Plantain Garden Fault in Haiti.

Tsunamis

Are giant sea waves triggered by earthquakes or landslides. The name is derived from the Japanese for “harbor wave,” because the waves often are noticed only when they approach shore.

Landslides

Is a general term for rapid downslope movement of soil or rock.

Floods

Are normal events that cause damage when people get in the way. As rivers carve and shape the landscape, they build broad floodplains, level expanses that are periodically inundated.

Beach Erosion

Occurs on all sandy shorelines because the motion of the waves is constantly redistributing sand and other sediments. One of the world’s longest and most spectacular sand beaches runs down the Atlantic Coast of North America from New England to Florida and around the Gulf of Mexico.

Weather

Refers to atmospheric conditions that occur locally over short periods of time—from minutes to hours or days. Familiar examples include rain, snow, clouds, winds, floods or thunderstorms.

Climate

Refers to the long-term regional or even global average of temperature, humidity and rainfall patterns over seasons, years or decades.

Greenhouse Effect

Is a warming that result when the atmosphere traps heat radiating from Earth toward space.

Global Warming

Is the long-term heating of Earth’s climate system observed since the pre-industrial period due to human activities, primarily fossil fuel burning, which increases heat-trapping greenhouse gas levels in Earth’s atmosphere

Climate Change

Is a long-term change in the average weather patterns that have come to define Earth’s local, regional and global climates.