ABSTRACT
The Geysers Valley is located in the territory of Kronotskiy State Natural Biosphere Reserve and is a tourist attraction. Geologically it is a canyon river valley composed by Pleistocenic lacustrine-volcanic hydrothermally altered deposits. Presently hydrothermal activity continues actively. The study rock strata are interbeded pumice litoclastic and pelitic tuffs. The article describes composition, structure and properties of them. It is shown the studied rocks are very sensitive to humidification their strength and deformation properties decrease sharply at water saturation. Moreover they erode readily. Experiments of alternating wetting – desiccation and freezing – thawing samples showed that some tuffs are destroyed after the first test cycle. Thus weak zones can form in zones of fracturing and higher permeability that subsequently become zones of separation and sliding. The map of slope processes distribution demonstrates the variety of slope processes formed in hydrothermally altered tuffaceous sediments in the Geysers Valley.
