Know the "rules" of interpreting rock sections... older than, younger than... meaning... MATERIALS
Monument Valley exercise -- Rules to remember ... Super____; Cross-______; Tilting means _____.
Roll out the nine chapters of Utah's geologic past... for Salt Lake County... note... not to scale for time... Chapter 1 is over half of the timeline!
Now... shift to LANDFORMS that we see and the processes that have made them look the way they do.
MANTRA!! TECTONICS RULE... All landforms are the product of TECTONICS and Erosion/Deposition. .
BIG CONCEPTS of PHYSICAL GEOGRAPHY
REGIONS – one of 5 "Great Themes" of geography
REGIONS are relatively extensive areas that are more similar within their boundaries than beyond their boundaries. They are drawn by people who have opinions as well as knowledge on the subject. Regions are based on spatial variation of a SPECIFIC CHARACTERISTIC. For example, regions based on surface water = drainage basins LINK.
Repeat: TECTONICS RULE!! 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
Regional – Interactive UNAVCO http://www.unavco.org/software/visualization/GPS-Velocity-Viewer/GPS-Velocity-Viewer.html
Local – evidence of GPS; evidence of seismic activity
Re-enact the spreading of the Basin and Range -- teams of two.
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
· 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
Tectonic setting – very stable, thick crust, isostatic equilibrium… (does not play well with others)
Big expressions: major massive mountainous terrain with broad “parks”
· 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)
Big expressions: big bold brassy red extensive, nearly-flat lying, relatively undisturbed, layered sedimentary bedrock exposed as plateaus, mesas, etc.
· Mesas, etc
· Low and erosional = canyons
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
What is essential for having a lake?
Great Salt Lake 1960s;
Great Salt Lake 1980s;
Concept of a hydrograph.
Concept of a closed basin... review... what has made the basins of the Basin and Range? Mantra!!
What if climate changed from hot and dry of the past 10,000 years to wetter and colder?
Present thoughts about why? and how often? Ice Ages have happened "recently"
Global Glacial versus Global Interglacial times LINK NOAA conveyor belt LINK
Calendar exercise (not for 2015)
Identify the province; point to (even if you don’t know their names) several landforms in the photo.