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Angkor Wat temple, mainly composed of sandstone blocks, displays a type of religious architecture that signifies the worldviews of the Khmer and Hindu religions. The temple is a part of a UNESCO World Heritage site. However, there are numerous occurrences of hollows, i.e., depression-like notches, that have developed at the base of its sandstone pillars due to wet-dry and salt weathering. These pillars are variably weathered due to differences in the directions of the pillar surfaces and galleries in the temple. In this study, we analyze the differences in the hollow depths based on the sandstone hardness and water content, as well as a 5-year record of the temperature and humidity in the galleries. The results show that the hollow depths are profound in the outsides of the inner pillars and shallow on the northern side of the first gallery. The hollow depth increases with increasing values obtained by multiplying water content and moisture fluctuations, resulting from direct insolation together with rainfall.

It is difficult to estimate weathering rates of rocks based on actual landforms. However, using stone-built architectures, artifacts, and traces of human activity on rock surfaces, weathering rates of rocks under weathering-limited conditions can be obtained easily because stone-built heritages, in general, have a geometrical shape and zero-datum levels. In addition, it is possible to estimate weathering rates of a millennium-scale and changes of rates up to a millennium scale. Many studies on weathering rates of rocks use stone-built heritages. This study reviews recent geomorphological studies that estimate weathering rates, and summarizes their trends. Most of the studies analyze gravestones and churches built since the 19 th and 11 th centuries, respectively. Such stone-built heritages are more commonly located in humid temperate areas. Weathering rates are estimated mainly from surface recession or surface loss of gravestones and church-building stones. The major three building stones─carbonate rocks (rate: 2⊖90 mm/ka) , sandstone (8⊖100 mm/ka) , and granite (5⊖65 mm/ka) ─have different ranges of weathering rates. Among these stones, the rates for carbonate rocks are sensitive to climatic conditions and atmospheric sulfur dioxide concentrations. The results of the studies reveal that weathering rates show an obvious dependence on aspects. North-facing surfaces tend to have lower rates than surfaces facing other cardinal directions because each surface has different temperature and moisture conditions due to insolation. Moreover, the studies reveal that temporal changes in weathering rates rarely fit a simple linear model. Changes in atmospheric acidity, landform development, and vegetation cover rapidly affect the intensity of weathering processes and cause fluctuations in weathering rates.Key words： stone-built cultural heritage, building stones, stone decay, physical environmental stress ：石造文化遺産，石材，石材劣化，自然環境ストレス ＊ 日本大学文理学部

Calcretes can be observed on the surface of old moraines around Batura Glacier in the upper Hunza Valley, Karakoram Mountains, Pakistan. They develop as a calcareous crust cementing small gravels under boulders. In order to understand the genesis of the calcrete crust, a variety of methods were employed: (i) study of mineralogy and geochemistry of a calcrete crust precipitated on the lateral moraine using X-ray diffractometer and electron probe microanalysis; (ii) analysis of solute chemistry of surface water and ice bodies around the Batura Glacier; and (iii) accelerator mass spectrometry 14 C dating of the crust itself. The results indicate that the calcrete crust has definite laminated layers composed of a fine-grain and compact calcite layer, and a mineral fragment layer. The chemical composition of the calcite layer is approximately 60% CaO and 1% MgO. The mineral fragment layer consists of rounded grain materials up to 0.2 mm in diameter. It shows a graded bedding structure with fine grains of quartz, albite and muscovite. Meanwhile, as the Paleozoic Pasu limestone is distributed around the terminal of Batura Glacier, Ca cations dissolve in the melt water of the glacier. Accordingly, the calcrete crust is precipitated by decreases in CO 2 partial pressure from glacier ice and evaporation of the melt water, including high concentration of Ca 2+ at ephemeral streams and small ponds stagnating between the moraine and glacial ice. On the basis of the AMS 14 C age, the calcrete is considered to have formed approximately 8200 calibrated years BP under the Batura glacial stage.