GEOG213-Lecutre 4-what controls topography

what are 5 Expressions of tectonics at Earth’s Surface

faults,foldsand fractures, volcanism, plutons

what is a way of dating geomorphic events

relative datings, mazama ash

what changes rocks respons to stress and strain

Rock’s response depends on

• Type of stress applied (compression, tension, shear)

• Duration & rate of applied stress

• Pressure & temperature environment

• Rock type

what is this

vertical dike (Topography and drainage patterns reflect differential resistance of rocks to weathering & erosion.)

what drainage pattern is shown here

radial drainage on mt saint helens

what drainage pattern is shown here

trellis drainage in rocky mts

8 types of drainage patterns

Structurally-controlled landscapes

Horizontally-bedded rocks •Dipping, bedded rocks •Folds and domes •Fractures •Faults •Extrusions •Intrusion

what are common features of horizontally bedded rocks

also cliff and bench toporaphy from differential erosion

geomorphic features of dipping, bedded rocks

what is this landform and what causes is

flatirons, dipping bedded rocks

what are 1 and 2

1: scar

2:dip slope

label the homoclinal ridge types

1:mesa

2:butte

3:scarp

4:dip slope

5:cuesta

6:hogback

7:razorback

whats this ridge type

scarp

what this ridge type

hogback or cuesta

what type of ridge is this

razor back but also trick questions its a vertical igenous dike

what type of fold is this and why?

anticline, A shape down, hinge line plunging down

syncline?

overturned anticline and syncline ?

recumbent syncline?

what happens when rocks fold

Weakening due to brittle deformation (fractures & faults

Young folds or very resistant beds: conformable landscape

Topographic inversion -synclinal ridge

what is the difference between non plunging and plunging folds

features of eroded, non plunging folds

features of eroded plunging anticlines

Homoclinal ridges form a V with scarps facing fold axis and converging in the direction of plunge

features of eroded plunging synclines

Homoclinal ridges for a V with scarps facing away from fold axis and diverging in the direction of plunge

what is the structural control on this landscape

eroded plunging syncline

what is the structural control on this landscape

idk-add later

A: eroded plunging syncline?

B: idk

what are 4 features of eroded domes

what is this

eroded dome

how do fractured rocks form

Breaks with no displacement

• Form due to contraction, pressure release or tectonics

• Erosion & drainage patterns depend on rock type

what drainage pattern is shown

contorted/deranged pattern

label the diagram

1:Fault scarp

2:Fault plane

3:strike

4:dip

5; handwall

6: footwall

7:throw

what types of faults are shown here

dip-slip faults (1 normal, 2 reverse fault)

normal fault

reverse

what type of faults are these

strike-slip

is this strike slip fault left or right lateral?

right lateral (the opposite side moves to the right based off where you stand)

left or right lateral?

left lateral

what are oblique-slip faults

how did this move

oblique slip-revrse fault-steep

normal fault (triangular facets)

idk

Not always. Debris aprons can cover original land surface. Topographic inversion may leave fault line scarps (erosional).

what forms result from cominations of normal faults

idk

right laateral strike slip

right lateral strike slip

what are two surface expressions of igneous activity

1)Volcanic landforms (extrusions) constructed at Earth’s surface • Lava flows, ejecta, ash, volcanoes

2) Plutonic landforms (intrusions) exhumed by erosion at Earth’s surface •Batholiths, domes, dikes, sills

three factors for volcanic shape

1. Chemical composition: silica content controls the viscosity of the magma and, consequently, its ability to plug up vents (Basaltic 50% silica; Andesitic 60% silica; Rhyolitic70% silica).

2. Eruption temperature: also controls viscosity and likelihood that lava will flow.

3. Gas Content: controls explosiveness and, ultimately, deposition patterns and flow types.

3 main spots of volcanoes

1) subduction zones

2) spreading centers

3)hotspots

two types of volcanic extrusions

1. Lava flows 2. Pyroclastic material

what type of lava is this

ropey (liquid)

what type of lava is this

blocky

what is a lobate flow

• Lobate flows are volcanic surface features characterized by rounded, bulbous lava lobes that extend outward from a vent or fissure.

• Common at spreading centers

what are marginal levees

Marginal lava levees are solidified walls of lava that form along the edges of a lava channel as the moving interior continues to flow

what are pressure ridges

Pressure ridges solidification & buckling:Pressure ridges are formed when the outer edges and surfaces of a lava flow begin to harden. If the advancing lava underneath becomes restricted, it may push up on the hardened crust, tilting it outward

what structure is this

lava tube

what are these

spatter cones

what process is occuring

topographic inversion

3 typess of pyroclastic material

Ash -< 2 mm

Lapilli –2-64 mm

Blocks (angular) & bombs (rounded) -> 64 mm

what type of volcano and why

shield: gentle slopes from low viscosity lava flows. Basaltic ex hawaii

what volcano is show and why

composite (stratovolcano): built by layers of lava and pyroclastic material

ex:mt saint helens

what volcano is shown and why

plug dome: viscous lava piles up in vent

what volcano is show

cinder cone (scoria)

what type of volcanos are shown

fissure at spreading centers

type of volcano and how it formed

tuya (table mountain), subglacial formation

how do igenous plutons form

example of an exhumed pluton

also yosemite and coast mountains