The slope stability of soft to semi-hard rocks has a close relation with the weathering of composing rocks. Auther surveyed the weathering of aged stone buildings such as ancient tombstones, and have been studying on the weathering mechanism and weathering speed of various kind of rocks. As the first step, obtaind results are as follows.
1. The rate of surface weathering on stone buildings differs with each direction of their face, and then it is evidently larger on the south face or the west. It seem that this weathering rate depent on the deger of temperature difference on their surface.
2. The defect by weathering on the surface of stone buildings is the maximum in depth at the place of 20-30 cm above their bacement. This defect is estimated to be related with reflection of heat, Jumping of rain water, etc. from basement stone or road surface.
3. The rate of weathering depends on property of rocks. The weathering defect extendery to 0.5 cm in depth from the surface requires a period of about 20 years on the rock having 100 kg/cm² of uniaxial compressive strength (dry), and a period of about 900 years on the rock of 2, 000 kg/cm².

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Micro-crack system in granitic rock was observed by means of scanning electron microscope, liquid penetrant test, soft X-ray photograph and polarized microscope with the following results;
(1) The liquid penetrant test is useful to observe the micro-crack system.
(2) The surface of micro-crack has generally irregular form probably due to the secondary mineral growth or corrision by the infiltration of ground water.
The evaluated results of the micro-crack system by statistical methods are as follows;
(1) The width distribution of micro-crack can be represented by N (t) Δt= K. t^-mΔt, where, K, m are the constants, t is the width and N (t) Δt is the number of micro-cracks in the distance between t and t+ Δt
(2) The m-value in the above equation tends to decrease with the increase of rock porosity.
(3) Only slight variations of the area of crack surface in a unit volume and the length of crack in a unit area are recognized in granitic rocks on the porosity of which ranges from 0.76% to 2.79%.

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Frost hummockの研究の大部分は高緯度地域もしくは寒冷地が対象になっているが, 中緯度地域に出現するfrost hummockについては報告がない。この論文は36°Nの位置にある八ケ岳火山東斜面に出現するfrost hummockについて調査した報告である。そしてfrost hummockが出現するには, 寒冷な気候のみでなく, 火山灰層がもっている組織が重要な役割を果していることがわかった。

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