EES #3

Tsunamis

A large ocean wave generated by vertical motions of the seafloor during an earthquake. These motions displace the entire column of water overlying the fault, creating bulges and depression in the water

Regolith

A layer of loose, heterogeneous material covering solid rock; it lacks substantial organic matter.

Soil

A natural layered mixture of mineral and organic material, plus air and water, that forms the interface between the lithosphere and atmosphere due to weathering; it differs from the underlying parent material and contains substantial organic content

Felsenmeer

A surface of angular, shattered rock produced by frost weathering

Thrust Fault

A type of fault, or break in the Earth's crust across which there has been relative movement, in which rocks of lower stratigraphic position are pushed up and over higher strata. They are often recognized because they place older rocks above younger.

Strike-slip or lateral faults

Caused by horizontal shear. The movement at a strike-slip fault is mainly horizontal and in opposite directions, similar to the way cars move in opposite directions on either side of the freeway. (Example: San Andreas Fault)

Shear

Causes the material to twist

Footwall/Hanging wall

In a reverse fault, the hanging wall is up and the footwall is down (convergent). In a normal fault, the hanging wall is down and the footwall is up

Normal Fault

Movement along a normal fault is partly horizontal and partly vertical. The horizontal movement pulls rock apart and stretches the crust. Vertical movement occurs as the stretching causes rock on one side of the fault to move down relative to the other side. (Example: The Basin and Range province in the southwestern United States)

Where most earthquakes occur

Plate boundaries

Tension

Pulls a material apart

Joints

Refers to a fracture or break in rock where there has been no movement in the plane of the fracture. These cracks occur parallel to the surface of the rocks and lets water through

Salt Weathering (haloclasty)

Salt weathering is a form of mechanical or physical weathering of rock. No chemical alteration of rock constituents is involved insalt weathering. The salt derives from an external source (capillary rising ground water, eolian origin, sea water along rocky coasts, atmospheric pollution).

Compression

Stress that decreases the volume of a material

Axis and Limbs

The axis of the fold is the line ofcurvature of any given layer. The limbs are the flanks of the fold and the hinge is where the flanks join together

Strain

The deformation of materials in response to stress

Biological Activity

the change or alteration of rocks or minerals by animal or plant. Any place you have life, it is actively breaking down rocks

Focus (hypocenter)

The first body waves generated by an earthquake spread out from the point of failure of crustal rocks. The point of failure where the waves originate is called the focus of the earthquake. It is usually several kilometers below the Earth's surface.

Dissolution of limestones to form caves

The largest and most abundant solutional caves are located in limestone. Limestone dissolves under the action of rainwater and groundwater charged with carbonic acid and naturally occurring organic acids.

Epicenter

The point on Earth's surface directly above the focus. Surface waves originate from the epicenter and spread out.

Faults

The resulting movement occurs along a weak region in the crustal rock. It is any fracture or system of fractures along which the Earth moves

L Waves

The third and slowest type of waves. They cause the ground to move sideways and up and down like ocean waves. They usually cause the most destruction because they cause the most movement of the ground and take the longest time to pass.

S Waves

They are slower than p waves. So they are the second set of waves to be felt. They have a motion that causes rocks to move perpendicular to the direction of the waves. The movement of these waves is similar to the movement of a jump rope that is jerked up and down at one end. The waves travel vertically to the other end.

Reverse Fault

They form as a result of horizontal and vertical compression that squeezes rock and creates shortening of the crust. This causes rock on ones side of a reverse fault to be pushed up relative to the other side. Reverse faulting can be seen near convergent plate boundaries.

P Waves

They squeeze and push rocks in the direction along with the waves are traveling. The compressional movement of p waves is similar to the movement along a loosely coiled wire.

Stress

Total force acting on crustal rocks per unit of area. When stress overcomes the strength of the rocks involved, movement occurs along fractures in the rocks

Importance of water during weathering

Water as a polar molecule. Water as it divides into charged particles (ions). On one side of the molecule its negative and one is positive. This gives water the means to attract and water begins the process of weathering because of its polar structure (one end has one charge and the other end has another charge). Water will break down into a hydrogen ion and they are very powerful in attracting and the H ion acts as an acid. Oxygen will attack many things and change them

Weathering Rinds

a discolored, chemically altered, outer zone or layer of a discrete rock fragment formed by the processes of weathering. The inner boundary of a weathering rind approximately parallels the outer surface of the rock fragment in which it has developed. Rock fragments with weathering rinds normally are discrete clasts ranging is size from pebbles to cobbles or boulders.

Thermal Stress

a residual stress introduced within a body resulting from a change in temperature.

Mechanical Weathering

a type of weathering in which rocks and minerals break down into smaller pieces. This process is also called physical weathering. It does not involve any change in a rocks composition; it only changes in the size and shape of the rock. A variety of factors are involved in this process such as changes in temperature and pressure.

Exfoliation (sheeting)

after a rock body is uplifted as a result of geological processes, fine cracks may develop in the rock due to a decrease in pressure. Over time, the outer layers of rocks can be stripped away in succession; similar to the way an onion's layers can be peeled. It often results in done-shaped formations. (Example: Moxham Mountain an Yosemite)

Oxidation

an important element in chemical weathering is oxygen. This is the process where the chemical reaction of oxygen mixes with other substances. Iron in rocks and minerals combine with oxygen in the water and air to form minerals with the oxidized form of iron. A common mineral that contains the oxidized form of iron is hematite.

Talus Cones

cones of debris ending in a slope

Importance of physical weathering for increasing surface area

o It increases the surface area of rock exposed to chemical weathering o The rate of weathering also depends on the surface area that is exposed. Mechanical weathering breaks rocks into smaller pieces. As the pieces get smaller, their surface area increases.

Root Wedging

roots of trees and other plants can exert pressure on rocks when they wedge themselves into the cracks in the rocks. As the roots grow and expand, they exert increasing amounts of pressure which often causes the rocks to split

Chemical Weathering

the process by which rocks and minerals undergo changes in their composition. Agents of this process include water, oxygen, carbon dioxide, and acid precipitation. The interaction of these agents with rock can cause some substances to dissolve, and some new minerals to form.

Weathering

the process in which materials on or near Earth's surface break down and change

Seismogram

the record produced by a seismometer (during an earthquake, the mass and the pen attached to it tend to stay at rest due to inertia, while the ground beneath shakes. The motion of the mass in relation to the frame is then registered on the paper with the recording tool, or is directly recorded onto a computer disk)

Erosion

the removal of weathered rock and soil from its original location. It can remove material through a number of different agents including running water, glaciers, wind, ocean currents, and waves.

Carbonation

when carbon dioxide combines with water in the atmosphere, it forms a very weak acid called carbonic acid that falls into Earth's surface as precipitation. When slightly acidic water from precipitation seeps into the ground and combines with carbon dioxide in the soil, carbonic acid becomes a stronger agent in the chemical weathering process.

Ice Wedging (heaving)

when it rains water fills the joints and water will freeze and ice expands. Fracture filled with water, freezes and causes a cone of debris. It happens in soils and causes surface to go up and break up