GLG 101 TEST 1

Using Fig. 4.13, (P. 108), assign a name to a fine-grained igneous rock composed of about 55% plagioclase feldspar, 30% hornblende (amphibole), and 20% pyroxene. Make sure you know how to use this diagram.

Andesite, it is in the row for "fine," & it also contains the right amounts listed above.

Why do canyons form in some places and valleys in others?

In places where a stream erodes down through its substrate faster than the walls of the streams collapse, a steep-walled slot canyon develops. In places where the walls collapse as fast as the stream downcuts, landslides and slumps gradually cause the slope of the walls to approach the angle of repose. When this happens, the stream channel lies at the floor of a valley whose cross-sectional shape resembles the letter V; this landform is called a V-Shaped Valley.

Explain why the viscosity of lavas is different for basalts and rhyolites and why this affects the manner of their eruption.

It says that mafic magmas are less viscous than felsic magmas, MAFIC because silicon-oxygen tetrahedras tend to link together in magma to create long chains that can't move past easily. Basaltic melt comes directly from the pool at the base of the crust, and the rhyolitic melt is caused by HEAT TRANSFER, so this means that the basaltic is hotter than rhyolitic melt. Hotter magma is less viscous. Rhyolitic may form a mound-like lava dome around the volcano's vent. Basaltic erupts in fountains, move long distances, and form thin lava flows.

Describe the three different kinds of material that can erupt from a volcano.

LAVA FLOWS- sometimes it races down the side of the mountain, and sometimes it builds into a rubble covered mound at the volcano's summit. It just depends on the viscosity of the lava. VOLCANIC DEPOSITS (Pyroclastic Debris)- Forms from lava that flies in the air and freezes. It also includes the debris formed when an eruption blasts apart preexisting volcanic rock that surrounds a volcano's vent, and the debris that accumulates after tumbling down the volcano in landslides or after being transported in water-rich slurries. VOLCANIC GAS- They come out of solution when the magma approaches the Earth's surface and pressure decreases. Most magma contains dissolved gases, including water, carbon dioxide, sulfur dioxide, and hydrogen sulfide.

How does discharge vary according to the stream's length, climate, and position along the stream course?

Length: Varies along the length because the velocity of water might increase or decrease, or the area of the stream might get bigger or smaller as you travel down a stream. Climate: the discharge in a temperate region increases in the downstream direction, because each tributary that enter the stream adds more water, whereas the discharge in an arid region may decrease downstream, as water seeps into the ground or evaporates. Position: If people divert the river's water for irrigation upstream, the discharge decreases downstream.

Where and why does a "backswamp" form on the floodplain of a meandering river?

The back swamps form in the in the low marshy region between the bluffs and natural levees of a floodplain because the WATER HAS NO WHERE TO DRAIN after a flood or rain, so it sits there and forms a swamp in the right climate. Friction slows the water on a floodplain, so a sheet of silt and mud settles out.

Explain how the vertical and horizontal components of an earthquake are detected on a seismograph.

Vertical-motion seismograph has a heavy weight (like a pendulum) suspended from a spring. The spring connects to a sturdy frame that has been bolted to the ground. A pen extends sideways from the weight and touches a vertical revolving cylinder of paper that has been connected to the seismograph frame. When an earthquake happens and causes the earth to shake the weight remains fixed, and the paper moves around under the pen. Horizontal is the same except it records shakes in the other direction.

How does a braided stream differ from a meandering stream?

Thus, during normal flow, the sediment settles out and the channel becomes choked with sediment. As a consequence, the stream divides into numerous strands weaving back and forth between elongated mounds or bars of gravel and sand. The result is a braided stream. Meandering streams wind back and forth like a snake.

What is a mineral, as geologists understand the term? How is this definition different from the everyday usage of the word?

To a geologist a mineral is a NATURALLY OCCURING SOLID, formed by geologic processes, that has a CRYSTALLINE structure and a definable CHEMICAL COMPOSITION. There are synthetic minerals produced in factories, but geologist do not consider these real minerals.

Why are some igneous rocks darker colored than others?

mafic rocks= black or dark gray intermediate rocks= lighter gray or greenish gray felsic rocks= light tan to pink or maroon.

Describe the difference between a pyroclastic flow and a lahar

A LAHAR is a slurry of ASH mixed with WATER. Rushes QUICKLY down valleys A PYROCLASTIC flow is an AVALANCHE of HOT ASH. Also called a glowing avalanche,

Why are some minerals considered gemstones? How do you make the facets on a gem?

A gemstone is a mineral that has special value because it is rare and people consider it beautiful. Facets are not the natural crystal facets, nor are they cleavage planes. The smooth facets on a gem are ground and polished surfaces made with a faceting machine.

Why is glass not a mineral?

A mineral is crystalline, and glass is not. In a mineral: atoms, ions, or molecules are ordered into a crystal lattice, like soldiers standing in formation, those in a glass are arranged in small clusters or chains that are neither oriented in the same way nor spaced at regular intervals.

What is a tsunami, and why does it form?

A tsunami is a giant wave traveling at speeds of about 800 km/hr (500mph). They are formed by the rise of the sea floor shoving up overlying water. Then the water from above the upthrust sea floor moves outward from above the fault zone.

Using sketches, explain how a volcanic caldera forms.

A volcanic caldera forms after major eruptions DRAIN THE MAGMA chamber and the CENTER of the volcano COLLAPSES into the hole of the drained magma chamber. Calderas can also form when a volcano explodes, blasting so much material in the air that only a portion of the volcano remains.

What factors control the viscosity(resistance to flow) of a melt?

Temperature, volatile content and silica content (in other words composition, temperature, and gas content)

Although coarse-grained rocks crystallize at depth they are often found along the crests of mountain ranges. Why? What has happened to any overlying volcanic rocks which may have risen to the surface above the cooling magma?

(Over long periods of geologic time, mountain building slowly uplifts huge masses of rock. Moving water, wind, and ice eventually strip away great thicknesses of overlying rock and expose the intrusive rock that has formed below.) So, the coarse-grained rock has been uplifted when mountains form and the overlying rock has been eroded away, and thats why we see coarse-grained rocks along mountain ranges.

Why are there so many different types of magmas?

1. SOURCE ROCK COMPOSITION: composition of a melt reflects the composition of the solid from which it was derived. 2. PARTIAL MELTING: only part of an original rock melts to produce magma. Usually only 2-30% of an original rock melts to produce magma at a given location, the temperature at sites never gets high enough to melt the entire original rock before the magma has a chance to migrate away from its source. 3. ASSIMILTATION (or contamination): as magma sits in a chamber before completely solidifying it may incorporate chemicals dissolved from the wall rocks of the chamber or from blocks that detached from the walls and sank into the magma. 4. MAGMA MIXING: Different magmas formed in different locations from different sources may enter a magma chamber. In some cases the originally distinct magmas mix to create a new, different magma. Thoroughly mixing a felsic magma with a mafic magma in equal proportions produces an intermediate magma.

What factors control the cooling time of a magma within the crust?

1.) The DEPTH of INTRUSION: magma intruded deep in the crust, where it is surrounded by warm wall rocks, cools more slowly than shallow intrusions, surrounded by cold wall rock. 2.) The SHAPE AND SIZE of a magma body: heat escapes from an intrusion at the intrusion's surface, so the greater the surface area for a given volume of intrusion, the faster it cools. Thus, a body of magma roughly with the same shape of a pancake cools faster than one with the shape of a melon. Since the ratio of surface area to volume increases as size decreases, a body of magma the size of a car cools faster than one the size of a ship. 3.) The PRESENCE of CIRCULATING GROUNDWATER: water passing through magma absorbs and carries away heat, much like the coolant that flows around an automobile engine.

Why do magmas rise from the depths to the surface of the Earth?

1.) it is LESS DENSE than surrounding rock, buoyancy drives magma upward (like a wooden block in water) or 2.) the weight of overlying rock creates pressure at depth that literally SQUEEZES MAGMA UPWARD. (like mud in toes when you step on it)

Describe the three processes that lead to the formation of magma.

1.) melting due to a DECREASE IN PRESSURE (DECOMPRESSION): if the pressure effecting a hot mantle rock decreases while the temperature remains unchanged, magma forms. This is because even if the temperature can be hot, if there is too much pressure it prevents atoms from breaking free of solid mineral crystals, but if pressure decreases this isn't a problem! 2.) Melting as a result of the ADDITION OF VOLATILE (FLUX MELTING): volatiles are substances such as water volatiles mix with hot rock, they help break chemical bonds. If you add volatiles to a solid, hot dry rock, the rock begins to melt. Adding volatiles decreases a rock's melting temperature. 3.) Melting as a result of HEAT TRANSFER from rising magma (heat-transfer melting):ie: hot fudge into ice cream. when magma from the mantle rises up into the crust, it brings heat. This rises the temperature of the surrounding crustal rock and in some cases is sufficient to melt part of the crustal rock.(H2O) and carbon dioxide (CO2) that evaporate easily and exist as gas at the earths surface. When

How does a stream-eroded landscape evolve as time passes?

At first the streams in the mountain range have steep gradients, drop over numerous rapids and waterfalls, and flow in deep valleys. As time passes, however, slumps and landslides move debris down mountainsides and into stream channels, and floods carry the debris away. All the while, downcutting continues to lower the channel floor. Overall, erosion and transportation transforms the rugged mountains into low, rounded hills. As this happens, once-narrow valleys broaden into wide floodplains with gentle gradients. As more time passes, even the hills erode away, and the landscape evolves almost into a new plain at an elevation close to the streams' base level.

Why does mica have such good cleavage?

Cleavage forms in directions where the BONDS HOLDING ATOMS together in the crystal are the WEAKEST. Mica has very weak bonds in one direction but strong bonds in the other two directions. Thus, it easily splits into parallel sheets; the surface of each sheet is a cleavage plane.

What is the prime characteristic that geologists use to separate minerals into classes?

Color, streak (color of powder it makes), luster (the ways its surface scatters light), hardness (ability to resist scratching), specific gravity (density), crystal habit (shape of a single well formed crystal face), special properties, fracture and cleavage: fracture (way it breaks based on atom arrangement) cleavage(directions where bonds holding atoms together are the weakest) conchoidal fractures(smoothly curving, clam-shaped surfaces

) What is the main difference between crystals which grow slowly in an undisturbed environment and those which develop during rapid cooling?

Crystals that form in an undisturbed environment develop large, coarse grained crystals. Crystals that form during rapid cooling develop small, fine grained crystals. Slow growers approach their inherent crystal shape and are larger.

What are the components of sediment load in a stream?

DISSOLVED Load: running water dissolves soluble minerals SUSPENDED Load: consists of tiny solid grains (silt or clay size) that swirl along with water without settling at the floor of the channel. BED Load: consists of larger particles (such as sand, pebbles, or cobbles) that bounce or roll along the stream floor.

Describe how deltas grow and develop. How do they differ from alluvial fans

Deltas develop where the running water of a stream enters standing water, the current slows, the stream loses competence, and sediment settles out. Geologists refer to any wedge of sediment formed at a river mouth as a delta, even though relatively few have the triangular shape of the Nile Delta. Where a fast-moving stream abruptly emerges from a mountain canyon into an open plain at the range front, the water that was once confined to a narrow channel can spread out over a broad surface. As a consequence, the water slows and abruptly drops its sedimentary load, and a gentle sloping apron of sediment (sand, gravel, and cobbles) called an alluvial fan accumulates.

How does a delta form?

Deltas form when RUNNING WATER of a stream (at it's mouth) enters a STANDING BODY of water, the current slows, and a wedge of sediment called a delta accumulates. (the stream loses competence, and sediment settles out.)

Why do some volcanic eruptions consist of mostly lava flows, while others are explosive and do not produce flows?

EFFUSIVE: produce mainly LAVA FLOWS. Low-viscosity BASALTIC lavas, can stream tens of hundreds of kilometers. During these eruptions lava may pool in lakes around the vent or spray up in fountains EXPLOSIVE: produce clouds and avalanches of PYROCLASTIC DEBRIS. Happen when gas expands in the rising magma but cannot escape. Eventually the pressure becomes so great that it blasts the lava, The result of that is a MUSHROOM CLOUD of coarse grained ash and lapilli which settle from the cloud close to the volcano and the finer ash settles farther away. These are explosive and DO NOT PRODUCE FLOWS because of their higher silica content and greater viscosity, andesitic lava cannot flow as easily as basaltic. Because the lava moves so slowly, the outside of the flow has time to solidify; so as it moves, the surface breaks up into angular blocks, and the whole flow looks like a jumble of rubble. RHYOLITIC lava is the MOST VICOUS because it is the most silicic and coolest. It accumulates in a lava dome or in a short bulbous flow. Sometimes rhyolitic lava freezes while still in the vent and then pushes upward as a column like spire or spine. INTERMEDIATE AND FELSIC LAVA is more viscous than basalt and may be more gas rich. As a result eruptions tend to be more explosive along with the previously solidified rock, out of the volcano. This can sometimes BLAST THE VOLCANO APART.

Describe elastic-rebound theory and the concept of stick-slip behavior.

Elastic-rebound theory is the concept that earthquakes happen because stresses build up, causing rock to bend elastically until slip on a fault occurs. Stick-slip behavior describes when earthquakes occur due to slip on a preexisting fault. Faults act like scars, they remain weaker than the surrounding crust. When stress builds up the fault slips before the stress becomes great enough to fracture surrounding intact rock.

What are the two major minerals in gabbro? in basalt? What is the difference between gabbro and basalt?

Gabbro and basalt are made of the same minerals, including Plagioclase, Olivine and a small amount of Amphibole. But they are made of the exact same minerals, the only difference is that Basalt is made of fine crystals and Gabbro is made from coarse crystals.

Explain how liquefaction occurs in an earthquake, and how it can cause damage.

Liquefaction occurs in beds of wet sand or silt where the ground is shaking and causes the sediment grains to try to settle together. But because of the spaces(pores) between grains are filled with water, water pressure in the pores increases and pushes the grains apart, and the wet silt or sand because a fluid-like slurry. It can cause damage because buildings whose foundations lie in liquefaction material may sink or even tip over.

Describe how meanders form and are cut off and the landforms that result from that process.

Meandering streams form where running waters travels over a broad floodplain underlain with soft substrate, in a region where the river has a very gentle gradient. If the stream starts out straight, natural variations in the water's depth causes the fastest moving current to swing back and forth. The water begins to cut away at the outer arc of where it is moving the fastest. Each curve begins to move sideways and to become more pronounced over time.The stream continues to cut away at the outside of the bank, forming a cut bank. On the inside, sediment settles and a point bar is eventually formed. Eventually, the meanders get so big that they erode into eachother and cut off from the rest of the stream, forming an oxbow lake, or an abandoned meander (if it dries out).

What is the relationship between the way in which silicon-oxygen tetrahedra bond in micas and that characteristic cleavage of mica?

Micas in some cases have WATER MOLECULES that fit between the SHEETS. Because of their structure they have a SINGLE strong CLEAVAGE in 1 direction

Why do some minerals occur as euhedral crystals, whereas others occur as anhedral grains?

Minerals occur as EUDRHAL crystals because their growth is uninhibited so that it displays WELL-FORMED CRYSTAL FACES. Other minerals that are without well formed crystal faces are called ANHEDRAL. They become anhedral because typically the GROWTH of minerals is RESTRICTED in one or more directions because of existing crystals that act as obstacles. In these cases minerals grow to fit the space that is available.

On the seismogram of an earthquake recorded at a seismic station in Paris, France, the S-wave arrives 6 minutes after the P-wave. On the seismogram obtained by a station in Mumbia, India, for the same earthquake, the difference between the P-wave and S-wave arrival times is 4 minutes. Which station is closer to the epicenter? From the information provided, can you pinpoint the location of the epicenter? Explain.

Mumbia, India, is closer to the epicenter because the time between the arrival of the P and S waves is shorter. The further away from the epicenter the larger the time between the arrival of the P and S waves. You cannot pinpoint the location of the epicenter because you need a third location to find an epicenter.

How are natural levees formed around rivers?

Natural levees are formed from a river FLOODING with water carrying stirred up SAND and MUD that spills out into the floodplain and SETTLES along the edge of the channel.

Describe the motions of the four types of seismic waves. Which are body waves, and which are surface waves?

P-waves: compressional waves can be generated by pushing and pulling on the end of a spring. The vibration direction is parallel to the direction of wave movement. Body waves S-waves: shear waves can be produced by moving the end of a rope up and down. As the waves pass through rock, the vibration direction is perpendicular to the direction of the wave movement. Body waves L-waves: as it passes, the ground surface moves back and forth like a slithering snake. Die out with increasing depth. Surface waves. R-waves: make the ground surface go up and down. Die out with increasing depth. Surface waves.

How do point bars develop?

Point bars develop on the inside edge of a meander because WATER SLOWs down so that its ability to carry sediment decreases and SEDIMENT ACCUMULATES in a wedge-shaped deposit.

There are huge granite batholiths all along the west coast of N. America (fig. 4.10D). Why are these a problem for Bowen's explanation for the origin of the igneous rocks?

Prediction from Bowen's model (hot bowl of melted rocks) for the origin of the igneous rock: For every mass of granite/rhyolite, there should be larger amounts of associated andesite/diorite and vastly larger amounts of basalt/ gabbro. SO: There should be huge amounts of Gabbro associated with these batholiths PROBLEM: They aren't there. Continents are mostly "granitic" (something is applying heat, plate tectonic describes it) MISSING ANDESITE?DIORITE

What role do streams have in the hydrologic cycle?

Running water generally flows in streams, ribbons of water confined to channels. Streams remove, or drain, excess water (runoff) from the landscape and carry it eventually to the sea. Streams also transport nutrients, and leave behind deposits of sediment.

Describe how streams and running water erode the Earth's surface.

SCOURING: running water removes loose fragments of sediment. BREAKING and LIFTING: the push of flowing water can break solid rock off the channel floor or walls. In addition, the flow over a clast can cause the clast to rise, or lift off the substrate. ABRASION: Sand-laden or gravel-laden water acts like sandpaper and grinds or rasps away at the channel floor and walls. DISSOLUTION: Running water dissolves soluble minerals as it passes, and carries the minerals away in a solution.

Describe the difference among shield volcanoes, stratovolcanoes, and cinder cones. How are these differences explained by the composition of their lavas and other factors?

SHIELD VOLCANOES: broad gentle DOMES, generally form from low-viscosity BASALTIC lava flows STRATOVOLCANOES: aka composite volcanoes, are large and CONE-SHAPED (steeper near the summit), and consist of alternating layers of lava, tephra, and debris (CLASSIC IMAGE of a volcano) CINDER CONES: consist of cone-shaped piles of TEPHRA. typically are symmetrical and have DEEP CRATERS at their summit.

How are long-term and short-term earthquake predictions made? What is the basis for determining a recurrence interval, and what does a recurrence interval mean?

Seismologists cannot make accurate short-term predictions.(on the time scale of hours to weeks) However some short term clues are the detection of foreshocks. Also they can predict with a precise laser surveying the ground. Long term predictions are based on the identification of the seismic zones and the recurrence interval (the average time between successive events).

Why are the eruptions of silicic volcanoes so violent?

Silicic volcanoes are caused by HEAT TRANSFER. Volatile-rich felsic lavas tend to erupt explosively and form THICK ASH and DEBRIS deposits. Felsic lava is more viscous than basalt, eruptions of these magma tend to be explosive- pg116 Sometimes viscous lava freezes at the top, blocking the rest of the lava from escaping, which builds up pressure until it explodes.

What types of structures are most prone to collapse in an earthquake? What types are most resistant to collapse?

Structures built on land underlain by weak mud that could liquefy are prone to collapse in an earthquake. Also structures built on top of, on, or at the base of steep escarpments could fail and produce landslides. Also, buildings downstream of dams are dangerous because they could crack and collapse causing a flood. Buildings that are resistant to collapse include ones that are wider at the base and that have cross beams added for strength. Wrapping a bridge's support columns in cable and bolting the span to the columns will prevent the bridge from collapsing so easily. Placing buildings on rollers or shock absorbers lessens the severity of the vibrations.

On what basis do mineralogists organize silicate minerals into distinct groups?

The classes of silicate minerals differ from one another by the way in which the silicon-oxygen tetrahedra are linked. They are organized into 7 groups (5 described) 1. Independent tetrahedra: tetrahedra are independent and do not share any oxygen atoms, attraction between positive ions holds them together, olivine & garnet 2. Single chains: tetrahedra link to form a chain by sharing two oxygen atoms, most common is pyroxenes. 3. Double chains: tetrahedra link to form a double chain by sharing two or three oxygen atoms, amphiboles 4. Sheet silicates: tetrahedra share three oxygen atoms & link to form 2-d sheets, occur in books of very thin sheets, strong cleavage in one direction sometimes water fits between sheets 5. Framework silicates: tetrahedra share all 4 oxygen atoms forms a 3-d structure. ie: feldspar, quartz most common are plagioclase and orthoclase

What are the dark spots you see when you look at the moon? The white areas? How did this happen?

The dark spots on the moon are BASALTS and the white areas are WHITE FELDSPAR. When the moon first formed the outer crust was made up of only white feldspar because it settles at the top as it crystallizes, then as objects hit the moon and cracked the crust, lava flowed into the cracks and crystallized to form basalt.

How is the depth to earthquake foci determined from seismograms?

The depth is determined in the difference between the arrival form the P waves and S waves.

Why is the lower Mississippi River from Baton Rouge to New Orleans in danger of disappearing?

The distinct lobes of the Mississippi Delta, a bird's-foot delta, suggest that AVULATIONS (when the river goes too far out to sea) the slope becomes too gentle, and stops flowing, a natural levee breaks, and the river shifts) have happened several times in the past 9000 years. New Orleans, built along one of the Mississippi's distributaries, may eventually lose its riverfront, for a break in the levee upstream of the city could divert the Mississippi into the Atchafalaya River channel. No more sand and mud is brought down into the original silt and it disappears. c) there is a shorter route to the sea that the river can take from a point just north of Baton Rouge. It will do so if the river is not contained.

What are the sources of heat in the earth? How did the first igneous rocks on the planet form?

The earth is hot inside, due to old heat left over from the planet's formation, as well as new heat produced by the DECAY OF RADIOACTIVE ELEMENTS. Although some igneous rocks solidify at the surface during volcanic eruptions such as those in Hawaii, a vastly greater volume results from SOLIDIFICATION OF MELT, out of sight. INTRUSIVE IGNEOUS rock: made by the FREEZING MAGMA UNDERGROUND, after it has pushed its way (intruded) into preexisting rock of the crust EXTRUSIVE INGENOUS rock: forms by the FREEZING LAVA ABOVE ground, after it spills out (extrudes) onto the surface of the earth and comes into contact with the atmosphere or ocean.

What is the evidence that the earth has a solid, inner iron core surrounded by a liquid iron core?

The evidence that the earth has a liquid is the study of S-waves because S-waves do not arrive at stations located between 103 and 180 degrees (S-wave shadow zone). This means that the S-wave cannot travel through the core at all, so the core has to be liquid. The evidence that the earth has a solid inner core comes from Lehmann discovering that P_WAVES passing through the core reflected off a boundary within the core, which creates the P-wave shadow zone. The only way for this to happen is to have something solid in the core, so she proposed that the core has a solid inner core surrounded by a liquid iron core.

What are the three kinds of earthquake waves? How can you determine the distance to an epicenter from the arrival times of P and S waves?

The first part P-waves and S-waves are in their own category, and L-waves and R-waves fall into the same category of surface waves, so thats why there are 3 instead of 4 kinds of earthquake waves.

How is the process of freezing magma similar to that of freezing water? How is it different?

The freezing of a liquid melt to form solid igneous rock represents the same phenomenon as liquid water to solid ice, except that IGNEOUS ROCK freezes at HIGHER temperatures- between 650 degrees C and 1,100 degrees C. It is also different because it contains many different compounds, not just water, so during freezing of molten rock, MANY DIFFERENT MINERALS FORM. & they don't all form at the same time.

What does the mixture of grain sizes in a porphyritic igneous rock indicate about its cooling history?

The grain size of crystalline rocks depends on the RATE OF COOLING. The presence of glass indicates that cooling happened so quickly that the atoms within a lava didn't have time to arrange into crystal lattices. Crystalline rocks form when a melt cools more slowly. In crystalline rocks, grain size depends on cooling time. A melt that cools rapidly, but not rapidly enough to make glass, forms fine-grained rock, because many crystal seeds form but none has time to grow large. A melt that cools very slowly forms a coarse-grained rock, because relatively few seeds form and each crystal has time to grow large.

8.) Describe the types of damage caused by earthquakes.

The modified mercalli intensity scale has a 1-12 rating of the damage caused by the earthquake. Types of damage: ground shaking and displacement, landslides, sediment liquefaction, fire, tsunami, and disease.

Describe the several ways that mineral crystals can form.

There are 5 ways: 1-SOLIDICATION OF A MELT, meaning the freezing of a liquid. ie: ice 2- by PRECIPITATION FROM A SOLID, meaning that the atoms, molecules, or ions dissolved in water bond together and separate out of the water ie: saltwater-> salt 3- SOLID-STATE DIFFUSION, the movement of atom or ions through a solid to arrange into a new crystal structure, a process that takes place very slowly. ie: garnets grown by diffusion of solid rock 4- BIOMINERALIZATION: minerals interface between physical and biological components of the earth system, when living organisms cause minerals to precipitate either within or on their bodies, or adjacent to their bodies. ie: calm mineral shells 5-PRECIPITATE DIRECTLY FROM GAS, occurs in volcanic vents or around geysers, steam enters the atmosphere and cools abruptly. ie: bright yellow sulfur deposits in volcanic regions

How does an "oxbow" lake develop next to a meandering river?

When the cut bank at the meander's ENTRANCE ERODES through the meander neck, and connects to the cut bank at its end, a CUTOFF develops. The meander that has been cut off is an oxbow lake if it REMAINS FILLED WITH WATER.