Stress(ed)? Stress Stress is the measure of the amount of force applied to a given area.
Effect on Rocks Stress is the force that acts on a rock to change its shape or volume Adds energy to the rock.
Deformation Deformation: Deformation: Any change in the shape or volume of Earth’s crust (caused by stress) Crust deforms from the force of plates colliding – Transform boundaries.
Relieving Stress Over time, stress builds up in the plates Eventually, the stress is released…
Compression Definition: Squeezing Effect on Rock: Makes rock layers thicker and shorter Associated Fault Type: – Reverse Fault Associated Plate Boundary: – Convergent Boundary
Tension Definition: Pulling apart Effect on Rock: – Stretches making rocks longer and thinner Associated Fault Type: – Normal Fault Associated Plate Boundary: – Divergent Boundary
Shear Definition: Moving in opposite directions – Think of shears or scissors Effect on Rock: – Stress distorts the shapes of rocks. Associated Fault Type: – Strike-Slip Associated Plate Boundary: – Transform
A fault is a break in the lithosphere Usually occur along plate boundaries, where the motions of plates compress, pull or shear the crust so much that the crust breaks. 3 Types of Faults – Strike Slip Fault – Normal Fault – Reverse Fault Faults
Below the fault plane Hanging (head) Wall Foot Wall
Hanging Wall – Lantern Foot Wall – Path
How rocks move determines how much friction there is between opposite sides of the fault Friction: Friction: a force that opposes the motion of one surface as it moves across another What about the surfaces causes friction? – It exist because surfaces are not perfectly smooth. Friction along Faults
Normal Fault diverging Force: Tension (diverging) with gravity Hanging wall: Moves down (with gravity)
Reverse Fault converging Force: Compression (converging) against gravity Hanging wall: Moves up (against gravity)
Strike-Slip Fault transform Force: Shear (transform) Rocks on both sides of the fault slide past each other
Landforms Topography: Topography: determined by its elevation, relief and landform All landforms have elevation and relief A landform region is an area where the topography is similar.
Elevation The height above sea-level on Earth’s surface.
Relief The difference between the highest point of elevation and the lowest parts of an area – have high relief – low relief. – Mountains – Plains
Plateaus Have high elevation and relief – Perfectly smooth on top May be really thick (1,500m), streams or rivers can cut through.
Plains Flat or gently rolling land with low relief and varying elevation. Depends on location… – Coastal Plains – Coastal Plains have low elevation at or near sea level along the coast. – Interior Plains – Interior Plains are away from the coast, causing varied elevation.
Mountains A landform with high elevation and relief Mountain Ranges Mountain Ranges are groups of mountains that are closely related in shape, structure and age.
Mountains formed From Faulting Normal Faults uplift blocks of rock and the hanging wall drops.
Mountains formed From Folding When continental plates collide, stress can cause rock layers to fold. Creates bends in the rock layers – Himalayas Mts. – Appalachian Mountains
Anticline A term used to describe folds in rocks “apex” An arching fold in the rock layers or “apex”
Syncline “slump” A downward pointing fold or “slump”
What to Work On Read Section 2.1 (pages 54-61) Answer section review questions (page 61, #1-4)