This paper discusses the following subjects concerning the Cretaceous system belonging to the Hetonaian series in the border region of Tokachi and Kushiro districts, Hokkaido.
1. This Cretaceous system is divided into three formations as follows, in descending order. Tokomuro sandy silt member Tomikawa formation Katsuhira mudstone member Tomikawa sandstone and conglomerate member Upper mudstone member Kawaruppu formation Lower sandstone member Kawakami formation
2. According to Iwamoto and Komura (1958), foraminiferal assemblages of this Cretraceous system are divided into the following two groups.
1) The assemblage of Kawakami and Kawaruppu formations: Dominant forms are Haplophragmoides horridus, H. obesus, H. spp. Bathysiphon alexanderi and Bramletteia ezoensis. Characteristic species are Involutina cretacea, I. gaultina, I. hashimotoi, Dorothia bulletta, D, hokkaidoana and Spiroplectammina grzybowskii.
2) The assemblage of Tomikawa formation: Numbers of species and individuals are few. It is characteristic that only the dominant forms of the lower group continue and other species are not found.
3. The author presumes the correlation between the Cretaceous system in this region and that in the Kushiro-Atsukeshi coastal region as follows, based on lithofacies and foraminiferal assemblages.

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The thick marine deposits of the Pliocene and Pleistocene are continuously developed in the Boso Peninsula. The lower part of them is a well-known gas-producing horizon. The Pleistocene succession of the Miura Peninsula intercalates non-marine sediments, accompanied with the unconformities, and it shows the advance and retreat of the sea. Therefore, the detailed time-stratigraphic correlation between the standard successions of two peninsulas is very important for the natural gas exploration and for the Quaternary geology of this region. The present attempt is made on the basis of the re-examination of the foraminifera fossil assemblages and lithostratigraphy.

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The sloughing of unconsolidated river sand (porosity about 50%, permeability 45 darcys) was measured with several kinds of liquids. These were water, CMC solutions, bentonite dispersions and bentonite-CMC dispersions.
The results obtained were as follows:
1. Water has a severe sloughing effect upon the unconsolidated sand.
2. Bentonite dispersions of high concentration (8%) reduce the amount of sloughing considerably but are not completely effective. When CMC is added to this dispersion, it becomes completely effective but is not economical.
3. CMC solutions are fairly effective in preventing sloughing but the effectiveness varies with type of the CMC.
4. When the most effective type of CMC is used, the concentration to prevent sloughing is comparatively high (0.1-0.5%), so that these CMC solutions are not economical.
5. Bentonite dispersions of low concentration (2%) plus CMC (0.07%) are both effective in preventing the sloughing and are economical.
6. Sands those were previously wet have a stronger tendency to slough than do dry sands.
7. Sands which contain dispersed clay have a weaker tendency to slough than do sands not containing clay.

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