Term | Definition |
Caldera | When a volcano collapses into its empty magma chamber after a particularly large eruption |
Volcanic Ash | Tephra |
Plinian Column | Ash and steam rising out of a volcano |
Batholith | Large exposures of intrusive rock, with more than 100 km2 exposed |
Stock | A smaller exposure of intrusive rock, that is less than 100 km2 |
1 degrees Succession | Primary biological succession occurs when plant species colonize a surface that has never had vegetation growing on it before |
Examples of Primary succession | when plants colonize a new lava flow, the surface of a mudflow, or a surface exposed by glacial retreat |
2 degrees succession | Secondary succession occurs when plants colonize a surface after a disturbance and the surface had previously been vegetated |
Examples of Secondary succession | re-vegetation after a fire, flood, etc. |
Anticline | Up-folded sedimentary rock caused by compression (convex upward) |
Overturned Fold | When a sedimentary rock is folded over on itself |
Oxidation | Combining with oxygen |
Hydration | When you add water to the mineral structure, it expands the material and makes it a softer mineral |
Hermatite | Colors rock red (Fe2 o3) iron, when it hydrates it forms limonite which is much softer and colors rocks yellow |
Carbonic Acid | Important in weathering limestone, marble, and other rocks containing calcium carbonate |
Unloading/ Expansion Jointing | Granite exposed on earth's surface so produces joints that are parallel to the surface of the rock and then is eroded away and produces an exfoliation dome (pressure release) |
Sinkholes | If the water table (the upper surface of the groundwater) is lowered, the roofs of the cavities may collapse |
Salt Crystallization | A biological weathering process where water moves through porous sandstone and emerges as a spring where the salts are exposed as a spring and begin to break down the rock |
Metamorphic Rocks | produced when a parent rock is subjected to intense pressure an/or temperature |
Gneiss | A foliated, layered metamorphic rock (has light/dark bands) |
Schistocity | parallel arrangement of platy minerals (mica) , refers to the shiny surface that is formed under intermediate intensity |
Marble | A non-foliated metamorphic rock that forms when limestone is metamorphosed, may be dolomite or calcite rich |
Slate | A foliated rock fine-grained metamorphic rock, dense, splits along flat planes (slatey cleavage) |
Quartzite | A non-foliated meatmorphic rock formed from metamorphism of quartz sandstone |
Schist | A foliated metamorphic rock that is rich in mica, micas are parallel to one another |
Gneissic Layering | alternate layers or bands of different mineral composition, the result of high grade, or high intensity metamorphism |
Clastic Sedimentary Rocks | formed from the weathered, transported, and deposited fragments of pre-exisitng rocks |
Non-Clastic Sedimentary Rocks | formed from chemical precipitation, usually involving carbonate or evaporite (salt) minerals, or from the accumulation of organic matter |
A Fault | a fracture in the Earth's surface crust along which movement occurs as rock on one side of the fault slides past rock on the other side of the fault |
Hanging Wall/ Foot Wall | The displacement along a normal fault is vertical- rock on side of the fault are down dropped (hanging wall) and the foot wall slides up |
Hot springs | The mixing of lava and water |
Hydrothermal (geothermal painting) | there is a fault where hot water precipitates out and the minerals are dissolves and paint the landscape |
Cinder Cone Volcanism | Short-term, effusive eruptions (only a few years then stop), magma is moving up the fault live very quickly so we find basaltic volcanism, the cinder cone is composed of cinders-coarse pumice or basalt |
Triangular facets | The erosion of the scarp produces blunt triangular-shaped facets at the end of each of the spurs coming from the up-thrown side of the fault |
Strike-slip/lateral faults/ transform | faults produced by SHEAR STRESS, the displacement is largely horizontal , when you look across the fault, objects may appear to have been displaced to the right or left of you |
Epicenter | Point on the earth's surface directly above the focus |
Focus | Point below the earth's surface where the movement of fault originates |
Moment (Richter) Magnitude Scale | Energy based physical scale, based on felt and the physical damage (2.0->8.0) |
Aftershock | a smaller earthquake that occurs after a larger earthquake |
Indonesian Earthquake 2004 | Off the coast of indonesia, one of the largest earthquakes ever recorded (9.0), huge after shock couple months after, the subduction zone triggered a tsunami (Sunda Trench) |
Great East Japan Earthquake 2011 | Geologic setting, aftershocks, tsunami, infrastructure damage-Fukushima Nuclear Power Plant |
Eolian Process | transport and deposition of sediment by wind, deposited typically in the form of a sand dune |
Differential weathering and erosion | cliff-forming: sandstones and limestones
slope-forming: shales and siltstones |
Mt St. Helens structure | classic cascade volcano, cone shape, high elevation
Being fed by subduction by the Juca Fuca Plate and North American Plate |
Mt St. Helens Location | in the cascade range, washington |
Mt St. Helens Bulge | part of the mountain that has been deformed by the building up of magma inside creating a swell |
How did Mt St. Helens erupt? | 5.0 magnitude earthquake, followed by a 5.1 earthquake which triggered a large landslide, the landslide uncorked the magma which triggered a vertical and lateral (horizontal) eruption |
The effects of the Mt St. Helens eruption | Huge crater created from eruption, part of mountain missing, blast zone with no trees left, ash deposited in rivers created various mudflows |
Lahars | volcanic mud flows, may result from melting glacial ice, as occurred at Mount St. Helens, produces unstratified, jumbled deposits |
Nuee ardente/pyroclastic flow | glowing cloud, a rapidly moving cloud of very hot gases, ash, and other tephra (anything blown out of the mountain) |
Volcanic Neck | solidified magma that crystallized in the conduit (pipeline) Shiprock NM largest example |
Obsidian | Glassy texture resulting from when the magma cools so quickly that no distinct crystals are able to form, glassy black, red, or brown |
Compression faulting | squeezing together, can result in deforming sedimentary rocks into a variety of folds, usually shortens or thickens the crust, thrust or reverse faults |
Tension Faulting | pulling apart, fractures perpendicular to the surface are produced, extension of the curst called normal faults |
Shear Stress Faulting | tear in the opposite direction (up and down) called strike-slip or lateral faults, horizontal displacement |
Synclines | Down folds (concave upward) U shaped |
Unroofed anticline | erosion removed the top of an anticline, the steeper slopes face towards the axis of the anticline |
Hogback | uplifted sedimentary beds left after an anticline has been eroded away |
Plunging folds | anticlines-steep slopes face toward the axis of the fold
synclines- steep slopes face away from the axis of the fold |
Mt Mazama | Crater Lake, bands of ash found in the sediment cored from lakes in the northwest |
Hydrolysis | adding water to bread down a substance-important in the weathering of feldspar (granite), produces clays and silica (quartz) in solution |
Chemical weathering (Athens) | results in rounded forms (spheroidal weathering), an expansion of material, and softer materials |
Exfoliation Dome | the pressure release, with unloading jointing |
Dripstones/Travertine | produces stalactites and stalagmites, limestone deposited by mineral springs, especially hot springs |
Karst landscape | forms in regions where dense, highlt jointed calcite-rich rocks are near the surface, and where the climate is good for chemical weathering |
Characteristic features of Karst landscape | sinkholes, towers of limestone, sinking or disappearing streams, dry valleys, caverns |
Tower Karst | Towers of limestone that are more resistant to weathering (mogotes) |
Mesa Verde | example of cliff dwellings produced by salt crystallization through biological weathering |
Conglomerate | A clastic sedimentary rock with rounded grains |
Sandstone | A clastic sedimentary rock with quartz and feldspar grains, feels gritty; visible sand |
Siltstone | A clastic sedimentary rock, grains not visible to the naked eye; rock feels gritty |
Shale | A clastic sedimentary rock, grains not visible to the naked eye, rock feels smooth, often layered |
Limestone | A chemical formed rock, that reacts to HCl, is precipitated from sea water, calcium carbonate is the main contributor |
foliated metamorphic rocks | rocks that have minerals arranged in a layered orientation , form from parent rocks |
Examples of foliated metamorphic rocks | slate, phyllite, schist, gneiss |
Non-foliated metamorphic rocks | no layers of minerals |
examples of non-foliated metamorphic rocks | Quartzite, marble, serpentinite |
Normal Faulting | anywhere that there is land being pulled apart (tension) and is accompanied by an extension of the crust |
Thrust/reverse faults | compression faulting (pushing together) vertical displacement |
Scarps | little cliffs associated with normal faulting |
Horst | upthrown side of normal faults, the mountain part |
Graben | means trench, the drop down valley of a normal fault |
Striations | scratch marks, show the movement of the fault |
The Bain and Range Province | a fault block mountain range created by normal faulting in Nevada. It is a series of upthrown mountain ranges (Horsts) separated by drop down basins (called grab end) |
right/ left lateral fronts | when you look across the fault, object may appear to have been displaced to the right or the left (strike slip lateral) |
San Andreas Fault | A strike-slip fault in California that separates the North American plate from the Pacific plate moved during famous San Francisco earthquake |
physical (mechanical) weathering | Break rock physically into smaller pieces, generally produces angular forms and fragments |
Chemical Weathering | break rock down by chemical processes, produces a new mineral substance as a result of a chemical change, usually involves water, produced more rounded shapes more chemical weathering in warmer places |
Modified Mercalli Intensity | Roman numerals based on human scale, will have high intensity when an earthquake occurs in a heavy populated area with lots of destruction to buildings |
Subduction Zone Mega Quake | When an earthquake originates in a subduction zone, this is where the biggest earth quakes take place, anticipated along the west coast, one happened in Indonesia 2004 Sunda Trench |
1906 San Francisco Earthquake | Along the San Andreas fault, 7.9 magnitude, the birth of modern earthquake science in the US, large fire broke out after creating most of the damage |
Liquefaction | A city built on top of underlying saturated lake sediments which during an earthquake loses strength and caused it to act like liquid (Mexico City) |
Tsunamis | result from large volcanic eruptions, submarine landslides, submarine earthquakes any geologic event that displaces a lot of sea water |
Brian Atwater | found record through paleoseismology (reconstructing prehistoric seismic activity) of the Cascadia subduction zone earthquake in the pacific northwest 9.0, he studied the trees killed in the 1700 earthquake, saltwater moved in and trees cannot survive |
Disappearing streams | streams that end abruptly, without joining a larger river, the streams are being swallowed up by sinkholes and continuing to flow underground |
Monocline | step-like fold on a fault caused by compression |
Mt Vesuvius/Pompeii | a glowing cloud (nuee ardent) completely covered the roman city of pompeii killing most of the citizens because of the ash and hot gases |
Pyroclastic | rocks formed from volcanic materials, clots of magma, volcanic ash, gas bubbles (pumice) |
Contact Metamorphism | is usually low-grade alteration, produced when rock is exposed by direct contact heat or pressure |
Columnar Jointing | Devils Tower, as the magma cools it shrinks and produces polygons or prismatic cracks that extends all the way down |
Frost Action | (freeze/thaw) breaks rock into pieces, particularly active in cold climates, high latitudes, high altitudes |
Regolth | mantle of decomposed rock over solid bedrock |
Weathering and Climate | Chemical-warm, wet climates, tropics
Mechanical-cold, dry, high latitudes and altitudes |
Firn | leftover snow from past season and in between snow and glacial ice |
Talus | broken pieces of rock that accumulate at the base of a slope, transported by gravity |
Spheroidal weathering | chemical weathering attacks corners and edges more effectively than flat surfaces, effective in the weathering of granite |
Joints | cracks or fractures in rock produced my mechanical weathering, increase surface area and accelerates chemical weathering by providing a pathway into the rock for water and other chemicals to penetrate |
Barchan Dunes | form where limited amount of sand, and wind from one direction, crescent shaped |
Transverse Dunes | (barachanoid ridges) wind from one direction but more sand than barchans needed, scallop lines |
Longitudinal Dunes | 2 different wind directions |
Star Dunes | wind blowing from 3 or more directions |