Tectonic Landforms
Landforms resulting from direct tectonic activity with little modification
by erosion (not structurally controlled landforms) Most are Holocene or
Late Quaternary in age)
Tectonic scarps
Fault valleys and fault block mountains
Landforms associated with folding
Appalachian
Valley and Ridge
Province
How is this
landscape
formed?
Is this tectonic
geomorphology?
Tectonic scarps
Scarp—
Scarp
—any steep slope along edge of
plateau, etc. May be tectonic, erosional,
depostional.
Tectonic scarpscarp-formed by direct tectonic
action
– Normal fault scarp
– Thrust fault scarp
– Fault line scarp
– Strike slip fault landforms
1
Normal fault scarps
Preserves original fault angle only when
very recent. Erosion reduces angle very
quickly, especially in unconsolidated
materials.
East slope;
Colorado
Rockies
D
U
Mountain front sinuosity
J = LJ/LS : index of fault
activity. The higher the
value, the less active the
fault.
A-B: initial activity; C-D: maximum relief;
E: tectonic quiescence, dominance of
fluvial activity.
2
Death Valley
Sonoma Range, Nevada
Normal Fault landforms
Sierra Nevadas
Sierra Nevadas
Ground View of fault
Red Canyon fault-Hebgen Earthquake
1959
3
Hebgen Scarp
2002, Denali fault, Alaska
Triangular facets
Produced by stream
erosion of fault scarp
4
Bottleneck canyon, Death Valley
Thrust faults don’t always
produce wellwell-defined scarps
Section at left being thrust over lighter sandstone at right
Keystone thrust, Nevada
Termination of a fault scarp
5
Fault--line scarps
Fault
No fault movement in present erosion
cycle.
(a) Continuity of lava flow shows that
scarp is erosion rather than fault
related.
(b) Scarp faces toward uplifted
side.
Landforms produce by strikestrike-slip faulting
Shutter ridges
6
Garlock fault-left lateral
Carrizo Plain-San Andreas
San Andreas
Offset drainages
San Andreas
San Jacinto fault
7
Sag Ponds
Alaska
San Andreas
Fault valleys and faultfault-block mountains
Horst
Graben
Types
– Oregon—
Oregon—flat lying rocks
– Basin and Range—
Range—tilted, deformed rocks, grabens
and half grabens in arid climate—
climate—basins are alluvial
desert basins—
basins—no throughthrough- flowing streams
– New Zealand—
Zealand—humid equivalent—
equivalent—through flowing
streams at bases of scarps
Oregon typetype-Iceland
Reykanes Peninsula
Thingvellir
8
Basin and Range Structure
Fault-block mountains-Nevada
Grabens
Garlock Fault, CA
Panamint Range, CA
9
Rift Valleys
Dead
Sea
rift
Red
Sea
Folding and Landforms
Monoclines
Topographic domes
– Salt Tectonics
Salt domes; Gulf Coast
Salt anticlines; Colorado Plateau
– Igneous Domes
Waterpocket Monocline, Utah
10
East Kaibab monocline, Arizona
Uplift of geomorphic surfaces
Shows relationship between geomorphology
and active tectonics.
Alaska
11 ft. uplift during 1964 earthquake
11
Moab anticline
ASTER image of salt dome, Iran
Igneous domes
Laccoliths, Texas
12