ANALYSIS of UTAH LANDFORMS

Reasons for Utah’s three physiographic provinces

BIG CONCEPTS of PHYSICAL GEOGRAPHY

REGIONS – major theme of geography

Physiographic provinces are (by definition) regions based on LANDFORMS. LINK to HUNT; UT-HUNT

Landforms result from processes of TECTONICS and EROSION/DEPOSITION … usually both sets of processes working in tandem. Reminder... LINK

TECTONICS is the Great Cause of Earth’s Uplifts (and down-warps, down-drops… but not down-cuts) Reminder... Earth's crust is THIN "deep in Earth's crust" is not proportionately far. LINK

ISOSTASY (floats like an iceberg) is included in TECTONICS as is volcanism and other igneous activity. LINK http://www.see.leeds.ac.uk/structure/dynamicearth/topo/isostasy.htm LINK re NAm; LINK re Bonneville

So… today… we’ll discuss

TECTONICS

Global --

Regional --

Local –

Global – USGS Dynamic Planet; DETAIL plates, USGS Plate Boundaries -- Look at the map. Dance of the Plates.

Regional – UNAVCO LINK And underlying mantle LINK and the result LINK

Local – evidence of GPS; evidence of seismic activity LINK; evidence of faults LINK Little Cottonwood; LINK to Utah Faults

LANDFORMS… how divide into regions? topography? LINK; same info, DEM? Sterner; physiographic provinces by landform; RiddAtwood; Ridd landforms, GA provinces.

BandR; RckyMth, ColoPlateau

and regions relate to human geography... cities... hospitals

ANALYSIS OF UTAH LANDFORMS by PHYSIOGRAPHIC PROVINCE

I. Basin and Range physiographic province

Tectonic setting – extensional and active… thin crust being ever stretched out and broken

BLOCKS

Landforms:

Big expressions: basins and ranges ... wonderful images by BOWEN (wendover looking east) or could do GOOGLE EARTH and, of course HAMBLIN House Range

Local expressions:

· closed basins (and closed basin lakes, sediment depo-centers, shorelines, etc) LINK

· fault related (scarp, chopped off mountain fronts with chopped off whatever-was-in-the-way, triangular facets, greatest snow on Earth, etc)

· ranges (run north south because extension pulls east west, low at both ends and high in the middle, usually one side steeper than the other because range front faults are usually not equally active)

· Low is depositional = basins with basin fill

Basin and Range characteristics LINK

II. Rocky Mountain physiographic province

Tectonic setting – very stable, thick crust, isostatic equilibrium… (does not play well with others)

Landforms: (plastic relief map) BOWEN Uintas looking west; HAMBLIN Uintas ; Google Earth (active)

Big expressions: major massive mountainous terrain with broad “parks”

Local expressions:

· Mountains of many shapes and sizes (depending on erosion/deposition histories)

· Drainages of many shapes and sizes

· Lots of glacial activity (more farther north)

· Both erosion and deposition. Both bedrock and sediments.

· Low and erosional = valleys, “open” not closed, marshes, fresh water lakes

III. Colorado Plateau physiographic province

Tectonic setting – very stable…. And rising isostatically (not fast and pretty evenly) because so much material is being eroded, the “base of the iceberg” rises … may be confusing… land surface gradually lowering, but rock units rising. Careful… the upwarps and downwarps pre-date “today’s” conditions. HAMBLIN - Grand Staircase; HAMBLIN - Gr Staircase Sketch; HAMBLIN Monument Valley; BOWEN Grand Co; BOWEN San Juan; Google Earth (live)

Landforms:

Big expressions: big bold brassy red extensive, nearly-flat lying, relatively undisturbed, layered sedimentary bedrock exposed as plateaus, mesas, etc.

Local expressions:

· Mesas, etc

· Low and erosional = canyons

BIG QUESTIONS:

How did the high country get high? – By province…

How did the low country get low? – By province…

Is the high country getting higher?

Is the low country getting lower?

Tectonics sets the stage…

Erosion / deposition act on it.

Calendar exercise

Identify the province; point to (even if you don’t know their names) several landforms in the photo.