Document Type : Research Paper
Authors
1 MSc, Faculty of Science, Tehran-Shomal Unit, Islamic Azad University, Iran
2 Assistant Professor, Soil Conservation and Watershed Management Research Institute, Iran
3 Professor, Faculty of Science, Tehran University, Iran
Abstract
This study is about the relation between erodibility rate and plasticity features of
Neogene Marl deposits of Gatchab and Gitcha in southeast of Garmsar. The erosions al
feature of Neogene sediments are rill, gully and waterway shapes. The depth of soil
sampling for rill and waterway types is from surface to 30-centimeter thickness and for
gully one is from head cut and all outcrop of gully bank. The engineering analyses for
sediments include liquid limit, plastic limit and plastic index and engineering
granulometry. On the basis of engineering classification of soil, the sediment of
Gatchab and Siahkoh mountains are fine grained soils with low to very low degree
cohesive, consequently low plastic limit and low internal consistency. The comparison
of the results between marl units of Gatchab and Gitcha area have shown the M2 unit
has low plasticity and high sensitive to erosion to other units M1 and M2. By the way,
the M1 unit is high resistance to water erosion in comparison to M3 unit. From all
aspect, Abundance of the lime and clay particle amounts is positive effects on
decreasing of sensitivity rate to erosion of Neogene deposits. The above mentioned
results base on plasticity features of Neogene deposits confirmed by field witness.
Keywords
)