Channeled Scablands

The Channeled Scablands (English as: " of canals criss-crossed wasteland " ) are a unique, formed by eroded landscape in the U.S. state of Washington. They were created by the cataclysmic Missoula Floods that swept repeatedly during the Pleistocene across eastern Washington and the Columbia River Plateau. J Harlen Bretz, the geologist created the concept of Scablands in a number of publications during the 1920s. The scientific debate on the origin of the Scablands lasted more than four decades, it is one of the major controversies in the history of earth sciences.

Geology

In contrast to the normal river valleys with V-section and glacial valleys with U-shaped cross -section, the valleys of the Channeled Scablands have rectangular cross-sections. They spread out over a large area of eastern Washington. The Talnetz the Scablands has an input and an output in the northeast to the southwest, the individual sections are branched and intertwined. In many places, unusual large scours and ripple marks are formed, which are much larger than those which often found in rivers.

The surface of the Scablands within large portions of the hard and mighty Columbia Plateau basalts. Before the floods of basalt was covered by a several meter thick layer of loess, which was completely washed away. The recurring floods have cut deep and leave high escarpments and witnesses mountains.

History of exploration

The first investigations by Bretz in the 1920s could not fully explain these structures. Due to the geological situation, the vorfand Bretz, he joined the short but tremendous floods, had to be flown at up to 2000 km ³ of water in a short time. For the origin of the water masses Bretz had no explanation, with this he not also dealt in the first place. He initially assumed that it was meltwater from glaciers of the last ice age in the area of Spokane, and called the flooding " Spokane Floods ".

The theory presented by Bretz met with bitter resistance from other geologists who wanted to explain the landscape of Scablands with uniformitarian theories.

1925 hit J. T. Pardee his colleagues Bretz before first that the sudden outflow of Eisstauseen, such as the failure of an ice dam, as occurs in the Icelandic Jökulhlaups, could produce the required amounts of water. Pardee had in 1910 assumed the existence of such Eisstauseen. Bretz did not elaborate on this proposal, since it appeared the origin of the water as not important, since one could see its impact in the field. However, Pardee pursued this idea over the next 30 years, collected more clues and evidence for his theory, and could confirm the relationship between the prehistoric Lake Missoula and the flood events eventually.

The theory of Pardee and Bretz were accepted only after decades of painstaking research and fierce scientific debate. It should be noted that the fiercest critics of the theory had never seen the Scablands with my own eyes. 1979 Bretz received recognition for developing one of the major concepts of Earth Sciences, the highest award of the Geological Society of America, the Penrose Medal.