Eric Clausen (2018). Probable Deep Erosion by Continental Ice Sheet Melt Water Floods: Chalk Buttes Area of Carter County, Montana, USA. International Journal of Geography and Geology, 7(1): 14-26. DOI: 10.18488/journal.10.2018.71.14.26
Topographic maps are used to determine erosional landform origins along the Little Missouri River-Powder River drainage divide in the Chalk Buttes areas of Carter County, Montana. Asymmetric drainage divides, drainage divide gaps, and isolated erosional remnants are used to determine a sequence of erosion events beginning with headward erosion of northeast-oriented Little Missouri River tributary valleys and ending with headward erosion of the deeper north-northeast and north-northwest oriented Powder River valley. Gaps notched into present day drainage divides and orientations of valley heads on either side of those gaps suggest many closely spaced southeast-oriented streams flowed across the region immediately prior to being captured by headward erosion of deeper north-oriented valleys. Buttes capped by horizontal Miocene Arikaree sandstones stand 500 feet (152 meters) or more above surrounding Little Missouri River tributary drainage basin elevations while the Powder River valley floor elevation is as much as 800 feet (244 meters) below those surrounding elevations. A water source could not be determined from the map evidence, however the study area is located to the south and west of a known continental ice sheet margin and large southeast-oriented ice-marginal melt water floods should have logically crossed the region.
This study documents how large volumes of southeast-oriented water of probable continental ice sheet melt water origin deeply eroded the Chalk Buttes area of Carter County in southeast Montana and suggests that at least one continental ice sheet deeply eroded the North American continent.
Erosion Surfaces of the Land Between Iznik-Mekece (Turkey)
Oznur YAZICI (2018). Erosion Surfaces of the Land Between Iznik-Mekece (Turkey). International Journal of Geography and Geology, 7(1): 1-13. DOI: 10.18488/journal.10.2018.71.1.13
The study area begins from the eastern part of the Lake Iznik which is in the southeast of Marmara Region in Northwest Turkey, and extends to Mekece. The area is part of the North Anatolian Fault Line, which has been operating since Miocene. Gemlik Gulf-Iznik Depression-Karadin Trough, and Pamuk Plain are the depression series from west to the east which developed due to the fault. During the cool and rainy periods of the Pleistocene, a part of the depression filled with water and became the Lake Iznik. In this period, there have been level changes on the lake due to the climate oscillations and some lacustrine terraces formed. Main geomorphological units in the study area are; high mountain ranges, high and low plateaus, plains and flat fields. Erosion surfaces, which spread widely in the study area, have been handled and evaluated according to Prof. Dr. Oğuz Erol’s method. Erosion surfaces were dated as Lower-Middle Miocene surfaces, Upper Miocene surfaces and Pliocene surfaces by applying Erol’s ‘Relation Method Between Slopes and Contour Lines’. Some of these surfaces are valuable for the settlement and agriculture because of the small amount of the slopes. It can be said that the research area has a polycyclic feature, and it is in the late youth stage of geomorphologic development.
This paper which is based on the author’s PhD thesis titled “The geomorphology of the land between Iznik-Mekece” describes erosion surfaces of the region according to Prof. Dr. Oğuz Erol’s ‘Relation Method between Slopes and Contour Lines’.