Idaho Geology

The Middle Rockies

Middle Rockies

Middle Rockies

• Ranges that are separated by broad valleys and plateaus (remember this description!). The ranges are the dominant features.

• Opposite description of Basin and Range

• Peaks in 8-10,000 ft. range

Geologic Origins• Folding for some ranges

• Faulting for some ranges (rows of fault blocks like B&R)

• Both folding and faulting for some ranges

Folding

Fault mountains may be simple horst and graben situations, or larger tilted fault blocks

Grand Tetons

Big Hole Mountains

Caribou Mountains

Blackfoot Mountains

Portneuf Mountains

Bear River Mountains

Mountain ranges

Blackfoot Mountains

Caribou MountainsGrey’s Lake in foreground

Portneuf Range

Bear River Mountains

Grand Tetons

Recognize this?

Blackfoot River

Portneuf River

Bear River

Gray’s River

Snake River

Teton River

Henry’s Fork

Rivers are important to this region

The Snake River begins in Jackson Lake, Wyoming, before flowing into Idaho

The first few miles in Idaho the river is actually Palisades Reservoir behind Palisades Dam, which controls floods and serves agricultural purposes (irrigation) as well as recreational needs (see next page).

Palisades Reservoir Palisades Dam

The Teton River flowing through Teton Valley

Henry’s Fork, one of the world’s premier fishing streams

Portneuf River

Blackfoot River Reservoir

Gray’s Lake

One of Idaho’s largest lakes, it is half in Utah

The Bear River drains the Middle Rockies around Bear Lake and the Bear River Mountains. It also drains the Eastern part of the Basin and Range

Soda Springs was so named because of large phosphate deposits discovered and

mined there even today.

Phosphate Mining

Phosphate Refining

• Baking reaction with sodium bicarbonate to produce carbon dioxide (CO2)

• Colas-Phosphoric Acid for fizz• Toothpaste-Dicalcium Phosphate Dihydrate as an

abrasive• Tooth Gels-Sodium Tripolyphosphate as a whitening

agent• Car Wash/dishwashing detergent-Sodium

Tripolyphosphate which softens water, removes soils and keeps soil from redepositing

• Fire Extinguishers-Mono- and Di- ammonium Phosphates as a fire retardant

• Latex Paint-Sodium Potassium Tripolyphosphate, Potassium Tripolyphosphate as a dispersing agent

• Fertilizers-Ammonium Phosphate as nutrient for plant growth

• Synthetic Rubber-Tetrapotassium Pyrophosphate as a catalyst

• Photocopier Toner-Tricalcium Phosphate as a dispersing agent

• Dyeing Wool-Diammonium Phosphate for control of pH in dye bath to allow even penetration of dye through the wool

• Explosives and pyrotechnics

Climate

• Fairly moderate and dry

• Summer average = 80 degrees

• Winter average low of 8 degrees

• Precipitation = 15” (at elevation)

• Snowfall heavy = 73” (at elevation)

• Rainshadow effect!

Rainshadow Effect

IDAHO

CASCADES AND SIERRA NEVADA

WASH/ORE

Vegetation

• Grassy valleys with irrigated farming between ranges

• Forested hills with most trees in moister low points

• Little vegetation on drier ridges

• Open forest encourages grazing/browsing

http://www.lavetarealty.com/Aspen_Forest.jpg

Towns and Cities

The End