Thursday, May 10, 2012

May 1, 2012. Malad Gorge, Idaho.

The Hawthornes are at Malad Gorge State Park
in Idaho, located just off I-84.
The 12 mile long Malad River
cut a 250 foot deep gorge out of the rock
and farmland that surrounds it.

 From the overlook parking area,
a footbridge spans the gorge,
offering an overhead view of
the Devil's Washbowl-
the large pool formed by the falls of the Malad River.

The Malad River crashes down stair step falls
 into the Devil's Washbowl,
and then cuts through a 250-foot gorge
on its way to the Snake River, 
2 1/2 miles downstream.
Malad Gorge offers a unique combination
of scenery, history, and geology
in a magnificent setting.
A Little History
The Malad River is formed by the union of the Big and Little Wood Rivers which flow from the Camas Prairie-Ketchum area of south central Idaho.  The river flows southwest approximately 15 miles before it enters the Snake River between Hagerman and Bliss.  The Malad River owes its name to an incident recorded by Alexander Ross, a Hudson Bay trapper.  In 1824, 37 members of Ross' party, when camped on this river, were made ill by eating locally trapped beaver.  Later, the trappers thought the beaver must have lived on some type of poisonous root.  From this incident, the trappers named the River "Riviere aux Malade," which means "Sickly River."

In modern times, water from the Malad River has been harnessed for power and irrigation.  An Idaho Power Company diversion dam, located approximately one mile downstream from here, diverts much of the water for hydro-electric power.  After the diverted water passes through the power substations, the water is routed to King Hill for irrigation.  This irrigation diversion project was one of the first in the state.

Geological History
The surrounding area's contours and drainage patterns have been influenced or developed by numerous local volcanoes which were active along the northern half of the Snake River Plain.  McKinney Butte, Gooding Butte, and Notch Butte were major active volcanoes at one time.  The major influence was exerted by the McKinney Butte lava flow.  At one time, the Snake River flowed north of Bliss and followed a well-defined canyon.  Lava flows from McKinney Butte filled this canyon and forced both the Snake and Wood Rivers to form a new channel at Malad Gorge.  Subsequent volcanic actions farther east progressively forced the Snake River into its present southern channel.  The Wood River drainage still reaches the Snake River via Malad Gorge.

Block faulting and damming of the Snake River during the Upper Pliocene and the Middle Pleistocene, approximately four million years ago, caused the deposition of lake and stream sediments which formed the Hagerman Lake Beds and the Glenns Ferry Formation. After periods of erosion, this area was then covered by Madson Basalt.  Madson Basalt is a very porous lava which permits the movement of large amounts of ground water as displayed by the numerous springs in the gorge.  The Malad Member of the Thousand Springs Basalt then flowed across the surface of the Madson Basalt.  The Malad Member is exposed in the upper layers of the gorge, and it comprises the surface rock over much of the area.

Malad Gorge was created by cataract (huge waterfall) retreat that followed a zig-zag course along zones of weakness in the rock.  These zones of weakness were the result of intersecting fractures in the lava rock.  The gorge consists of a "main" section that extends from the Snake River canyon east about one mile to a junction.  At the junction, a "north" branch extends about one quarter mile east to the extinct "west" cataract. A "south" branch then extends from the junction east about one mile from here at the "east" cataract.  In the early stages, a broad zone of cataracts was present, approximately two miles west of here, pouring directly into the Snake River canyon.  As the gorge began to develop by cataract retreat, the Malad cataract captured the water that had been going over the other canyon wall cataracts.  The joint control was favorable for a more rapid retreat in gorge development.  The cataract retreated about 1 1/4 miles to the "west" cataract.  A considerable amount of water went over the "west" cataract which can be evidenced by its width and by the water-scoured and pot-holed rock at the lip of the cataract.  Prior to development of the south branch, water flowed across the present location of the "east" cataract to the "west" cataract as evidenced by an extensive set of rapids and pot-holed bedrock leading across the upland between the two existing branches.  As the south branch of the gorge retreated from the junction, it eventually captured the water that had been going over the "west" cataract and beheaded the north segment of the gorge.  The "east" cataract is not as wide as the "west" cataract, suggesting that the river flow was smaller by the time that the south branch of the gorge retreated to its present location.  A very marked reduction in water flow then took place.  The Malad River has cut a deep, narrow notch into the lip of the "east" cataract.  Even allowing for the flow reduction caused by irrigation diversion, it is obvious that the present river flow is much too small to have made the cataracts in Malad Gorge.  During the Pleistocene, approximately one million years ago, precipitation was much greater in the headwaters of the Wood River drainage and the annual snow-pack was much greater.  All these factors suggest that the river had a much larger flow than it does now and that the river probably had a very large flow during the spring run-off.

Since sedimentary deposits underlie the volcanic edges of the gorge. The soft silts are giving way under the weight of the rigid basalt blocks causing slumps.  The large slump blocks are an outstanding example of an important geologic process in action today.

During the Bonneville Flood, "melon gravels" were deposited across the mouth of Malad Gorge.  These large eroded rocks shaped like melons were washed to their present location by a great catastrophic flood which emptied the great Lake Bonneville.  This huge lake, of which Salt Lake is the residue, once covered a great deal of what is now southern Idaho and most of northern Utah.  At its maximum stage, Lake Bonneville covered nearly 20,000 square miles and was over 1000 feet deep.  During the Pleistocene, the ancient lake ruptured and flood water, 200 to 600 feet deep, passed through this area cutting gorges and tumbling large rocks in its wake.  The lake drained northward through the Snake River to the Columbia River and the Pacific Ocean.

Early Inhabitants
Archeologically speaking, two Snake River Plain cultures can be dated back 8000 years.  Prior to that time, there was no clear record of regional cultures on the Snake River Plain.  The regional cultures appear to have developed from the way of life of earlier food collectors who first occupied the Snake River Plain perhaps 15,000 years ago. These first inhabitants were big game hunters, but may have fished and gathered wild plant food.
During the 15,000 years that man has occupied the Snake River Plain, there have been important environmental changes.  The earliest occupation corresponds to the time of the mid-Pinedale glaciation in the northern Rocky Mountains.  The close of this geoclassical period, about 12,500 years ago, was represented by a series of physical changes in the landscape of the Snake River Plain and its flanking valleys.  Neither the land forms nor the sediments were new in type, but there was a change in topographic position in the development of alluvial fans and drainage patterns for the region.  The end of the mid-Pinedale glaciation was associated with a substantial discharge of meltwater, so that deep canyons were left with a bedrock floor while mid and downstream areas accumulated large gravel deposits.  Each time environmental changes took place, cultural changes would also have to take place in order to insure survival.  The reduced environmental fluctuations, during the last 7000 years, created a relatively stable environment in which large mammals and men could gradually increase in numbers as part of the succession which led to the permanent occupation of this area.

The South Hills culture occupied the western Snake River Plain and its flanking valleys which included this area, the Owyhee tablelands, and the Boise Basin.  The South Hills culture is the archeological expression for the Western Shoshone culture.  Since density and prosperity of the native population depended upon the environment, the area between Shoshone Falls and American Falls was exceptionally infertile thus forcing the natives to remain downstream west of Twin Falls.  The inhabitants preferred to remain downstream near their stores of salmon and in proximity to one another for protection against raids from an unidentified Oregon tribe.  The salmon, making three runs a year up the Snake River to this area, quickly became the staple food for the local inhabitants.  The best fishing area was near Hagerman at the Upper and Lower Salmon Falls.  The salmon were caught with nets, hooks, and especially with dams and weirs.  There were three villages between Hagerman and Bliss.  One village was four miles below Hagerman at a place the Indians called "Saihunupi" or tule canyon.  This canyon could have been what is now known as Malad Gorge.  The second village, called "Pazin-tumb"  (pazin: thistle + tumb: rock or rocky pass), was eight miles below Hagerman.  The third village, called "Otoumb" (oto: silty soil), was near Bliss.  Between these villages and scattered on tributaries of the Snake River, several individual families made their camps.  The Indians continued to use the salmon from the Snake River, between Salmon Falls and Bliss, even to the turn of the 20th Century.  Shortly after 1900, all Indian activities in this area stopped due to the lack of salmon runs caused by the construction of Swan Falls Dam on the Snake Rive south of Boise.

Always look down.
Don't want to miss the special surprises.
In this case, the wildflowers.

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