Presentation on theme: "Geology of Idaho The Northern Rockies. Northern Rockies Basin & Range Middle Rockies The 3 mountainous regions of Idaho."— Presentation transcript:
Geology of Idaho The Northern Rockies
Northern Rockies Basin & Range Middle Rockies The 3 mountainous regions of Idaho
Northern Rockies This is the largest mountainous area of Idaho covering about ½ of the state
4 Mountain ranges of the N. Rockies
B I t e r o t Bitterroots form part of the boundary with Montana and part of the U.S. Continental Divide
12,655 feet> The Lost River Range has Idaho’s highest point, Mt. Borah, rising 12,655 feet
Lost River Range
Lost River Range has several peaks over 10,000 feet Towering over Hell’s Canyon on the western edge of Idaho is another spectacular set (nearly 9000 feet) of peaks………..
Seven Devils Range
Longer than the Snake? Rivers flowing from the NR carry runoff from rain and snow. The Salmon River, flowing 420 miles, is the longest river in Idaho.
The Salmon runs from Stanley Basin at the foot of Galena Pass, through the Northern Rockies and joining the Snake River 40 miles south of Lewiston
The River of No Return Named for the deeply eroded valleys and the boiling rapids experienced by rafters
Feferal recognition of the magnificence of this region in isolation, beauty, and uniqueness
Kootenai River 2.Pend Oreille River 3.Priest River 4.Coeur d’Alene River 5.St. Joe River 6.St. Maries River 7.Clearwater River 8.Lochsa River 9.Selway River 10. Salmon River 11. Payette River 12. Boise River 13. Lost Rivers Rivers of the Northern Rockies
River valleys provide transportation routes
The rivers themselves may become routes of transport, too!
Dworshak Dam Dams on some rivers provide opportunities for recreation, irrigation, hydroelectric power, and flood control 717 feet high and over a half mile long!
The Purcell Lobe of the Cordilleran Ice Sheet moved down into the Panhandle of Idaho and created lakes
Glacially scoured lakes Lake Pend Oreille Priest Lake
Glacially dammed by glacial moraines blocking valleys Spirit Lake Hauser Lake Hayden Lake
Glacially dammed Lake Coeur d’Alene
Alpine glaciers left lakes, too!
Glacially scoured lakes Redfish Lake Payette Lake
Geologic Origins Volcanic activity Folding and faulting Glaciation Water erosion
100 million years ago the 2 nd largest batholith in the world formed in Idaho
A large, granitic formation that is the core of the Northern Rocky Mts.
Evidence of the heat that remains
With the magma came many minerals that later formed valuable metal ores like gold, silver, and lead, as well as quartz
In some places, pressures within the earth caused layers in the crust of the earth to fold or crack (fault). This created mountain ridges and valleys.
Examples of fault block mountains
Thrust fault scarp near Stanley, up and over the other side of the fault line
Glaciation in Idaho 15,000 years ago ice covered all of NR that was below 8000 feet in elevation 1000’s of feet thick carving/scouring the landscape of NR in many places Great weight caused glacial ice to move As they moved down V river valleys they remodeled them into U glacier valleys Left piles of debris called moraines Left moraine dams and flat valley floors Left many alpine features in the NR
Pend Oreille - Carved by ice Coeur d’Alene – River valley blocked by terminal moraine Ross Point Hill (terminal moraine) overlooking Rathdrum Prairie (glacial flood deposits)
Water erosion figures into the geologic landforms of the N. Rockies leaving many V- shaped valleys
Alluvial fans often formed at the openings of the v- shaped valleys
ClimateClimate - precipitation Wetter than the rest of the state Moisture forced out as air force to rise over the Rockies –20 inches in Post Falls –40 inches in Wallace/Mullan area Precipitation in Panhandle = 30” Southcentral = 7-26 Snowfall heavy because of elevation
This is caused by moist air which flows through the Columbia Gorge in the Cascades from the Pacific and to the Northern Rockies. It then is wrung dry as it climbs the face of the Rockies. return
It is approximately 60-75” annually in most places; McCall = 151”;Stanley, Challis = 94” return
Climate - temperature Low winter average = 20 degrees Southcentral average = 10 degrees Summer average = 84 degrees in the panhandle, 88 in southcentral back
Northern Rockies are the most heavily forested part of Idaho.
Idaho is the most forested Rocky Mt. state!
Mountains and forests of the West
Red cedar, Douglas fir, hemlock, spruce, lodgepole pine, and Western white pine provide a rich resource to Idaho
White pine (Idaho state tree) – 180 feet tall and 2-4 feet in diameter
The largest stand of white pine in the world is located here, in the St. Joe National Forest
The forest understory includes syringa, ninebark, Oregon grape, wild rose, huckleberry, and snowberry (shown here).