Disintegration of marl slopes in Israel

Disintegration of marl slopes in Israel is directly related to the climatic characteristics of the region even where water is not an obvious component of the environment. Seasonal contrasts between long, dry summers and short, wet winters are manifested by wide ranges in temperature (13–26°C) and water content (5−>42 percent) within the marl. These variations lead to both solution and aggregation of carbonate material in the marl. Chemical disintegration in summer followed by mechanical disintegration in winter causes progressive weakening of the marl. The repeated wetting and drying results in the formation of an open texture in the marl. Scanning electron microscope (SEM) observations made over several seasons on marl from freshly excavated slopes confirm the progressive disintegration from the slope's surface to a depth of at least 1.50 m. Solution holes, channels, and gaps between aggregates and matrix, formed during the summer, greatly increase the effective porosity and permeability of the marl. Water infiltration in the winter results in the mechanical washing out of fine material to the surface of the slope by throughflow and piping.