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Drumhellerchanneledscablands

Drumheller Channels.

The 
Drumheller Channels are within the Drumheller Channels National Natural Landmark area, and are the most significant example in the Columbia Plateau of basalt butte-and-basin channeled scablands. This National Natural Landmark is an extensively eroded landscape, located in south central Washingtoncharacterized by hundreds of isolated, steep-sided hills (buttes) surrounded by a braided network of numerous channels, all but one of which are currently dry. It is a classic example of the tremendous erosive powers of extremely large floods such as those that reformed the Columbia Plateau volcanic terrain during the late Pleistocene glacial Missoula Floods.

The Drumheller Channels connects the Quincy Basin, which lies to north, with the Othello Basin on the south. It can be reached most easily from Othello, Washington approximately 8 km (5.0 mi) northwest on McManamon Road, then north on Morgan Lake Road which passes through the Drumheller Channels region. The north/south Morgan Lake Road (gravel) passes through the heart of the channels following Crab Creek. Hikes can be taken, including an interpretive trail, from the wetlands along Crab Creek to the views from an isolated butte, that allow the hiker to gain a sense of this unique landscape. The Drumheller Channels can also be seen from the paved State Route 262 which runs to the north of the area along the top of the Potholes Reservoir dam (which has inundated part of the scablands) and from the west side from the heights of the Frenchman Hills.

HistoryEdit

Geologist J Harlen Bretz coined the term "channeled scablands" in a series of papers written in the 1920s. The debate on the origin of the Scablands that ensued for four decades became one of the great controversies in the history of earth science.  Bretz encountered resistance to his theories from the geology establishment of the day. The geology establishment was resistant to such a sweeping theory for the origin of a broad landscape for a variety of reasons, including lack of familiarity with the remote areas of the interior Pacific Northwest where the research was based, and the lack of status and reputation of Bretz in the eyes of the largely Ivy League-based geology elites. Furthermore, his theory implied the potential possibilities of a Biblical flood, which the scientific community strongly rejects. Bretz defended his theories, kicking off a 40 year debate over the origin of the Scablands until his view was widely accepted and acknowledged, that a massive flood reformed much of Eastern Washington. 

Bretz conducted research and published many papers during the 1920s describing the Channeled Scablands. His theories of how they were formed required short but immense floods (500 cubic miles of water), for which Bretz had no explanation. Bretz's theories met with vehement opposition from geologists of the day, who tried to explain the features with uniformitarian theories.

J.T. Pardee first suggested in 1925 to Bretz that the draining of a glacial lake could account for flows of the magnitude needed. Pardee continued his research over the next 30 years, collecting and analyzing evidence that eventually identified Lake Missoula as the source of the Missoula Floods and creator of the Channeled Scablands.

Pardee's and Bretz's theories were accepted only after decades of painstaking work and fierce scientific debate. Research on open-channel hydraulics in the 1970s put Bretz's theories on solid scientific ground. In 1979 Bretz received the highest medal of the Geological Society of America, the Penrose Medal, to recognize that he had developed one of the great ideas in the earth sciences.

GeologyEdit

The Okanogan lobe of the Cordilleran Glacier moved down the Okanogan River valley and blocked the ancient route of the Columbia River, backing up water to create Lake Spokane. Initially water discharged from Lake Spokane by running up through the head of Grand Coulee and down through Foster Coulee to rejoin the Columbia River. As the glacier moved further south, Foster Coulee was cut off and the Columbia River then discharged through Moses Coulee, which runs southward slightly to the east of the ancient and current course of the Columbia. As the Okanogan lobe grew, it blocked Moses Coulee as well; the Columbia found the next lowest route through the region which was eroded to become the modern Grand Coulee. Flowing across the current Grand Coulee & Dry Falls regions, the ice age Columbia then entered the Quincy Basin & joined Crab Creek, following Crab Creek’s course southward past the Frenchman Hills and turning west to run along the north face of the Saddle Mountains & rejoin the previous and modern course of the Columbia River just above the main water gap in the Saddle Mountains, Sentinel Gap.

The Missoula Floods discharged into Lake Spokane, through the Grand Coulee, greatly enlarging it, passed over Dry Falls and then ponded in and inundated the Quincy Basin, covering over 1500 km² (585 mi²) and creating the Ephrata Fan (a deposit of boulders, cobbles, and pebbles where the flood waters discharged into the basin). The discharge volume was so great that water overflowed Lake Spokane in multiple places & also reached the Quincy Basin via the Telford-Crab Creek scablands and Lind Coulee (both entering the basin from the east). When floodwaters encountered the Frenchman Hills, their level was high enough that, although the bulk of the water passed through the Crab Creek drainage, some water spilled west over the low points of three divides along Evergreen and Babcock ridges to reach the Columbia river channel at Frenchman Coulee to the southwest, Potholes Coulee to the north central and Crater Coulee to the northwest. The bulk of the floodwaters took the easiest path, straight south through the Drumheller Channels stretch of Crab Creek.[4][5]

The elevation drop of the floodwaters as they passed through the Drumheller Channels was greater than 50 meters (160 ft) over a distance of 20 km (12 mi) with gradiants locally ranging from 2–12 m/km). This hydraulic head combined with a flow depth of from 60 to 120 meters (200 – 400 ft) provided the energy to achieve flood flow velocities as high as 30 m/s (65 mph), which eroded the topsoil and underlying basalt, gouging the complex network of channels, basins, potholes and buttes that are found there even today. Examples of scabland features, such as large kolk-excavated potholes, provide evidence of the tremendous powers of the floods.[5]

There is a unique character to the Drumheller Channels; unlike most other Channeled Scabland zones, no single centralized channel or major cataracts were formed. In the Drumheller Channels the floodwaters passing through in a broad cascade of 13 – 20 km (8 to 12 miles) in width. Bretz recorded 150 distinct channels and over 180 rock basins in this region. Many of the low areas, including Upper Goose Lake, are filled by water seeping in through cracks in the basalt bedrock, which are connected with Potholes Reservoir to the north.

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