EOS Midterm 1 Terms

Qualities of a Mineral

Naturally occurring, inorganic, solid, crystalline, specific composition

Intrusive Igneous Rock

Slow-Cooling

Extrusive Igneous Rock

Fast Cooling

Weathering

Physical and Chemical breakdown of rocks at Earth’s surface

Erosion

Removal of weathered material by transport processes

Unconformity

A surface that represents significant missing time

Artesian Groundwater

Found at high pressure

Porosity

Percent of a rock or sediment by volume that is void

Permeability

Numerical expression of how easily water can pass through a material

Well Digging

Permeability more important that porosity

Unsaturated Zone

Air fills some doors in the rock

Saturated Zone/Phreatic Zone

Area below ground where pores are filled with water

Water Table

Boundary between phreatic zone and unsaturated zone

Recharge

Entrance of water into saturated zone

Discharge / Base Flow

Release of groundwater into lakes and rivers

Streams in Arid Environments

Formed by runoff, not base flow

Gauging Station

Measures level of water in a stream

Open Channel Flow

Controlled by elevation and momentum, occurs at 1 atm

Saturated Flow

Controlled by elevation and pressure, very slow

Aquifer

Area of permeable Earth

Aquitard

Non-permeable Earth

Unconfined Aquifer

Aquifer reaches to the water table

Flowing Artesian Piezometer

If water in a piezometer rises above the surface

Artesian piezometer

Water level in piezometer rises above aquifer

Drawdown

Pumping water from a well lowers the water table, can pull up saltwater

Electrolytes

Ions dissolved in water which can beneficial for health

Electroneutrality

Natural solutions have a charge balance. If not present, there are undetected ions.

TDS

Total Dissolved Solids - Measure of concentration of dissolved material in water. Rain has lowest level, groundwater has a higher level.

Brackish Water

Water which has a TDS greater than freshwater, less than saltwater

Brine

Water with a TDS over 100,000 mg/l, saltier than saltwater

Exogenic Hydrological Cycle

Energy for the cycle comes from the sun

Karstification

Dissolution or chemical decay of a rock that produces landforms by rock removal

Karst

Landforms created by karstification (caves or sinkholes), often in limestone

Carbonation

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Tower Karst

Limestone towers created by Karstification. Rocks above limestone protect the towers from weathering

Cave Development

Soil

Layer formed at Earth’s surface by the buildup of weathered materials

Dissolution

Minerals dissolve into component ions in a solution, form of weathering

Carbonation

Carbonate materials react with carbonic acid, weathering of limestone and dolomite

Hydrolysis

Minerals react with water or hydrogen ions in water

Clay

Refers to both a particle size, and a type of particle with a specific structure

Hydration and Dehydration Weathering

Minerals attach or release water from chemical bonds, especially clay

Oxidation / Reduction Weathering

Weathering by combination of a mineral with oxygen, such as rusting

Pebble Ghosts

Pebbles with low density, constituents removed by weathering

Frost Line

Depth of frost growth

Frost Heave

Freezing and thawing of subsurface groundwater can lift building foundations

Exfoliation

Peeling of surface layers of a rock, caused by pressure, chemical weathering, or hydration. Can cause cliff face collapse

Types of Mechanical Weathering

Impact and Abrasion, Wetting and Drying, Freeze Thaw, Crystal Growth, and Heating and Cooling (Insolation Weathering)

Insolation Weathering

Caused by wildfires

Natural Arches

Caused by Exfoliation

Grusification

Granular, grain by grain, disintegration of a coarse grained rock

Differential Weathering

Different rates of weathering for adjacent rocks and structures

Weathering in Arid Climates

Mostly Mechanical, very slow

Weathering in humid Climates

Mostly chemical, relatively fast

Soil formation

Soils not deposited, formed by alteration of existing materials

Surficial Deposits

Non - Lithified (non-rock) materials at Earth’s surface

Order of Soil Horizons

Top to Bottom: O, A, B, C

O-Horizon

Uppermost soil layer, 90% organic matter, dark brown, absent in arid regions

A-Horizon

Second soil layer, mostly mineral material, called zone of leaching

Soil leaching

Cations stripped from soil through heavy weathering (dissolution)

B Horizon

Third soil layer, Red or yellow, called zone of accumulation

Translocation

Accumulation of solid byproducts of weathering in soil

C Horizon

Lowest soil layer, Lightly altered parent material

Dynamic Equilibrium

Soil erosion rate = soil formation rate, land lowers over time. Most soils never get here

Soil Development Rate

Very fast at start, as soil becomes deeper, formation slows

Paleosols

Soils formed at some time in the past which are no longer forming

Buried Paleosol

Paleosol buried by accumulating sediment or volcanic deposit

Relict Paleosol

Soil that formed sometime in the past, but is still at the surface. No longer forming

Mass Movement

Erosion and transport of materials downslope due to gravity, occurs when shear-stress exceeds shear strength. Ex: Rockslides and Mudslides

Coherent vs. Incoherent Mass movement

Coheren - Rigid Mass, Incoherent - Mixes while moving

Fall

Mass movement in a vertical direction, toppling or tumbling

Slide

Rapid mass movement, coherent movement on a slip plane

Flow

Incoherent mass movement of saturated sediment (Mudslides and lahars)

Slump

Slide on a curved surface with toe exhibiting non-coherent mass movement

Creep

Very slow, non coherent mass movement of soil debris and sediment, caused by freeze thaw or wetting and drying

Triggering Mechanisms of Mass Movement

Earthquakes, Volcanoes, Precipitation, Fire, Fracture, Plant removal

Permafrost Melting

Causes instability on the surface, can cause structure collapse

Solifluction

Creep over permafrost

Mass Movement Descriptive Terms

Poorly sorted (mix of grain sizes), poorly defined bedding, muddy conglomerate

Colluvium

Any deposit created by mass movement

Collapse Breccia

Breccia formed by collapse of a cave ceiling

Talus

Colluvium with no fine particles sitting at angle of repose (Highest angle it can sit at) due to rockfalls