Stratigraphically, soilhardness was surveyed on the shallow landslides in Mt. Aso. Around hard layer, sliding surfaces often formed. The significant regression was found between the logarithm of the depth of soil layer and soilhardness (ash with humus p<O.O1, brown weathered ash p<0.05), which indicates the effect of consolidation. However, the layers whose soilhardness are bigger than 25mm are not always deep-seated layers. The Stratigraphy of hard layers was compared by tephra. Then it was found that soil-solidification is not always seen in a specific layer, so there is no reason to presume that soil-solidification occurred due to the characteristics of the ash. Thus not only consolidation caused by the accumulation of ash but also cementation is found to be concerned with soil-solidification. The solidification of ash is in progress also in the surface layers, so it was suggested that it complicates the physical characteristics of soil layer.