Where is the thinnest lithosphere?

at ridges

what do Plate motions do

Put stress on boundaries and existing faults.

Elastic Deformation

Rocks and faults deform elastically in response to building stress.

what is Strain

The change in shape of rock due to stress.

how does an earthquake occur

Occurs when stress exceeds the ability of rocks to lock faults.

Focus

The original starting point of an earthquake.

Brittle Deformation

Deformation that causes rocks to break.

Ductile Deformation

Deformation that allows rocks to bend without breaking.

Normal Fault

A fault where the footwall moves up due to tensional stress.

Reverse Fault

A fault where the footwall moves down due to compressional stress.

Thrust Fault

Similar to a reverse fault but with a shallower angle relative to Earth's surface.

Synclines

Rock strata that dip towards the hinge of a fold.

Axial Plane

An imaginary plane that contains the successive hinges of a fold.

Geological Structures

Configurations formed in rocks due to tectonic forces.

Uniformitarianism

The principle that Earth processes we observe today occured in the past and are recorded in rocks.

Numerical Age

The quantifiable age of a rock or fossil.

Relative Age

The age of rocks or fossils in comparison to others.

Superposition Principle

In undisturbed sedimentary rocks, the oldest layer is at the bottom.

Lateral Continuity

Sedimentary layers extend in all directions until they thin out.

Cross-Cutting Relationships

Rocks that cut across other rocks are younger than the rocks they cut.

Anthropocene

A proposed new geological epoch characterized by significant human impact on Earth's geology.

Erratics

Boulder-sized foreign rocks transported by glaciers.

Kettle Lakes

Small, roughly circular lakes formed by glaciers.

Moraines

Narrow hills composed of unsorted sediments left by glaciers.

Horn

Mountain peaks eroded by glacier action, representing local maximum elevation.

Arete

Ridges that separate glaciated valleys.

Cirque

Bowl-shaped valleys formed by glacial erosion.

Rock Flour

A fine powder created by a glacier as it scrapes over bedrock.

Ductile Structures

Structures formed when rocks bend rather than break.

Sedimentary Basin

Low-lying areas where sediment accumulates, often adjacent to mountain ranges.

Basins

Areas where younger rock is found at the hinge in geological folds.

Where is the thickest lithosphere

at mountains

where does ductile deformation take place

in the asthenosphere

where does brittle deformation take place?

in the lithosphere

in a dome, where are the oldest rocks located?

at the center of the dome in the hinge

in a basin, where are the oldest rocks located?

at the edges of the basin

tools to infer relative age

Original horizontality, Superposition, Lateral continuity, Cross Cutting

What is a Glacier?

A large mass of ice that moves slowly over land, formed from compacted snow.

What is glacial retreat?

The backward movement of the glacier front due to melting or loss of ice.

What is glacial till?

Unsorted sediment deposited directly by glacial ice as it melts.

how can you tell the difference between a valley carved by water vs. a valley carved by a glacier.

Glaciers have steeper sides and a U-shaped profile, while water-carved valleys tend to have a V-shaped profile and gentler slopes.

how do glaciers transport erratics?

weather erodes boulder from bedrock, allowing the glacier to pick it up and transport it as it moves equator-ward. when glacier retreats, it move back pole-ward, depositing the boulder.