Details Title: Exam 2 Description: sed and meta rocks, geo history and petroleum Total Flash Cards: 63 Created: 11/05/2008 17:51:25		New Users: To study from this flashcard set, or to create your own your own study flash cards, REGISTER HERE. Existing Users: CLICK HERE. Additional Geology Flashcards
Cards in this set: Term sedimentary rock cycle Definition rock-weather down-transport sediment-deposit-lithify-sedimentary rock Term mechanical weathering Definition physically breaking down rock, produces smaller pieces, and rocks and mineral fragments(clasts) Term physical weathering Definition rain, streams, wind, thermal stress(expanding and contracting), glaciers, gravity, freeze-thaw cycles Term chemical weathering Definition involves chemical weathering ex: K-feldspar added to kaolinite clay breaks the rock down Term Rock changes as they transport further Definition reduction in grain size, increase in sorting, increase in rounding, fine particles travel farther down stream Term deposition environments Definition continental(valley,edge of glacier,stream, lake, desert), transitional(delta, beach, tidal flats), marine(shallow continental shelf, deep ocean) Term clastic rocks Definition rocks that form from clasts or rock fragments getting pressed together Term chemical sedimentary rocks Definition usually form at or near their place of deposition usually from seawater Term biological sediments Definition form at or near their place of deposition but are the result of mineral precipitation within organisms as they grow. ex: shells or corals Term cross bedding Definition bedded material deposited by wind or water at angles usually on steep downslopes Term mud forms____, sand forms_____, gravel forms _____ Definition shale, sandstone, conglomerate Term carbonate sedimentary rocks Definition ex: limestone form in marine environments w/ calcium carbonate(shells). lights helps to foster the growth of carbonate deposits Term conglomerate Definition forms in river or continental environments where pebbles are gravel are deposited Term sandstone Definition forms in transitional environments where finer particles settle out once the current slows and cannot suspend sediments anymore Term siltstone, shale, mudstone Definition usually forms in marine environments or on the edges of the transitional environments where the current ceases to suspend even the finest particles Term metamorphic processes that change rocks Definition solid state changes that result in rearrangements of atoms (heat, pressure, fluid activity) Term heat Definition comes from the mantle and the core(leftover heat from the formation of earth) and from radioactive decay Term geothermal gradient Definition for every km of depth the temperature increases 25-30 deg C Term confining pressure Definition equal pressure in all directions from layers of rock Term differential pressure Definition unequal pressure coming more from one direction that from others ex: tectonic pressure Term fluid activity Definition speeds up metamorphic process, can help atoms throughout the lattice framework of a rock easier to cause rearrangement and metamorphism happen easier Term time Definition not a process but a major factor in the metamorphism of rocks Term contact metamorphism Definition comes from a magma pluton metamorphosing the surrounding country rock, may come from hot water convection current Term regional metamorphism Definition a large area subjected to higher than normal heat/pressure. Usually involves tectonic activity and differential pressure. produces foliated rocks. most common form of metamorphism Term grade of metamorphism Definition low grade-muscovite, medium grade-biotite,garnet, high grade-partial melt Term principles of correlation Definition sedimentary layers usually start out horizontally, younger layers always overlie older layers, cross-cutting layers are younger than the affected layers, inclusions are always older than the enclosing rock body Term relative dating Definition we can date things in relation to each other but not an exact age. use the principles of correlation Term absolute dating Definition finding the exact numerical age of a rock or fossil by using isotopic dating which uses naturally occurring radioactive elements Term half-life Definition time required for half of the original atom to decay into the daughter(other type)of atom. doesn't change with temperature, pressure, chemistry or anything else, complications-lose isotopes through weathering or fluids, or metamorphism can reset isotopic composition to younger age Term catastrophism Definition earth's surface formed in a great cataclysim. sudden violent events, unknowable cause by events not now operating Term uniformitarianism Definition earth's surface is a product of processes still happening today. processes in the past were the same as today, observed rates of change are slow so earth must be very old Term actualism Definition uniformity of processes but rates of processes have varied with time. linear history, consequences of long geologic time periods-slow processes have large effect, rare catastrophic events will occur, earth is affected by gradual and catastrophic processes, all changes are a result of natural processes Term geologic time Definition eon, era, period, epoch Term deep time Definition geologic time is so long that even rare events have occurred repeatedly Term strike Definition the compass direction that a rock layer points Term dip Definition the amount of tilt that the rock layer has from horizontal Term dip-slip fault Definition movement of the blocks up or down Term strike-slip fault Definition the movement of the blocks occurs horizontally Term normal fault Definition a dip-slip fault that occurs from tensional forces that pull rocks apart Term reverse fault Definition dip-slip fault that occurs from compressive forces that push rocks together Term left-lateral fault Definition the body on the left moves down Term right-lateral fault Definition the body on the right moves down Term anticlines Definition the arches or peaks that occur Term synclines Definition the troughs or valleys Term asymmetrical folds Definition when the folds are not perpendicular to the ground Term overturned folds Definition when the folds are tilted beyond vertical Term tensional tectonics Definition brittle crusts pull apart and create valleys or depressions like the Rhine River Valley or the Red Sea rift Term compressive tectonics Definition plates colliding that either produce megafaults(huge earthquakes or tidal waves), or large mountain ranges like the Himalaya Term shearing tectonics Definition bodies move past each other horizontally, not much internal damage to rocks, San Andreas Fault Term petroleum Definition mixture of different kinds of hydrocarbons (hydrogen and carbon) Term formation of petroleum Definition dead marine algae and plankton sinks to bottom, buried, organic rich rock (black shale) pressure and heat (oil-90-160C) forms oil. usually for oil 4-6 km and gas up to 9 km Term finding oil deposits Definition need a source rock(organic rich shale), reservoir (rock layer that is permeable with space between pores so that fluid can flow through ex: sandstone), trap (tight impermeable rock layer so oil can accumulate) Term finding petroleum Definition usually accumulates in the anticlines, use seismic exploration to find discontinuity Term reserves Definition definite supplies, we found them, know they exist Term resources Definition projected supplies, we hope they are there Term peak oil Definition rate of oil production will peak and then decline in a symmetrical bell shaped curve developed by Hubbard Term problems with breaking with oil Definition cheap easy form of energy, most concentrated form of energy we have in abundance and easy access to Term demand and price of oil Definition tied to supplies, as supplies get tighter, prices becomes more volatile and in general prices go up Term coal Definition 50% of US electricity, cheap and it is very abundant main problem is the environmental impact of coal Term formation of coal Definition forms from dead plant life (twigs,leaves, etc) in a marshy environment. the higher the temps for formation, the higher the carbon content of coal Term mining techniques for coal Definition open pit mining- large open holes, coal is removed and then rocks are replaced. contour mining- go around the mountain and strip the coal from the sides of a landscape. mountain top removal- the top of a mountain is removed and put in a valley to get at the coal within the mountain Term negative impacts of coal on the environment Definition contributor of CO2, acid rain, mercury contamination, and metal contamination. large amounts of ash and sulfer Term alternative energy resources Definition positives: less of an environmental impact, more sustainable no shortage negatives: expensive to develop, oil is profitable and quashes other energy sources, disposal and safety (nuclear)