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Geology of Idaho The Northern Rockies. Northern Rockies Basin & Range Middle Rockies The 3 mountainous regions of Idaho.

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Presentation on theme: "Geology of Idaho The Northern Rockies. Northern Rockies Basin & Range Middle Rockies The 3 mountainous regions of Idaho."— Presentation transcript:

1 Geology of Idaho The Northern Rockies

2 Northern Rockies Basin & Range Middle Rockies The 3 mountainous regions of Idaho

3 Northern Rockies This is the largest mountainous area of Idaho covering about ½ of the state

4 Mountain ranges of the N. Rockies

5 B I t e r o t Bitterroots form part of the boundary with Montana and part of the U.S. Continental Divide

6 12,655 feet> The Lost River Range has Idaho’s highest point, Mt. Borah, rising 12,655 feet

7 Lost River Range

8 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………..

9 Seven Devils Range 1 2 345 67

10 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.

11 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

12 The River of No Return Named for the deeply eroded valleys and the boiling rapids experienced by rafters

13 Feferal recognition of the magnificence of this region in isolation, beauty, and uniqueness

14 1 2 3 4 5 6 78 9 10 11 12 13 1.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

15 River valleys provide transportation routes

16 The rivers themselves may become routes of transport, too!

17 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!

18 The Purcell Lobe of the Cordilleran Ice Sheet moved down into the Panhandle of Idaho and created lakes

19 Glacially scoured lakes Lake Pend Oreille Priest Lake

20 Glacially dammed by glacial moraines blocking valleys Spirit Lake Hauser Lake Hayden Lake

21 Glacially dammed Lake Coeur d’Alene

22 Alpine glaciers left lakes, too!

23 Glacially scoured lakes Redfish Lake Payette Lake

24 Geologic Origins Volcanic activity Folding and faulting Glaciation Water erosion

25 100 million years ago the 2 nd largest batholith in the world formed in Idaho

26 A large, granitic formation that is the core of the Northern Rocky Mts.


28 Evidence of the heat that remains

29 With the magma came many minerals that later formed valuable metal ores like gold, silver, and lead, as well as quartz

30 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.


32 Examples of fault block mountains

33 Thrust fault scarp near Stanley, up and over the other side of the fault line


35 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

36 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)

37 Water erosion figures into the geologic landforms of the N. Rockies leaving many V- shaped valleys

38 Alluvial fans often formed at the openings of the v- shaped valleys

39 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

40 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

41 It is approximately 60-75” annually in most places; McCall = 151”;Stanley, Challis = 94” return

42 Climate - temperature Low winter average = 20 degrees Southcentral average = 10 degrees Summer average = 84 degrees in the panhandle, 88 in southcentral back

43 Northern Rockies are the most heavily forested part of Idaho.

44 Idaho is the most forested Rocky Mt. state!

45 Mountains and forests of the West

46 Red cedar, Douglas fir, hemlock, spruce, lodgepole pine, and Western white pine provide a rich resource to Idaho

47 White pine (Idaho state tree) – 180 feet tall and 2-4 feet in diameter

48 The largest stand of white pine in the world is located here, in the St. Joe National Forest

49 The forest understory includes syringa, ninebark, Oregon grape, wild rose, huckleberry, and snowberry (shown here).

50 End of the day, end of the presentation!


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