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146 are generally nearly cylindrical. The weathered bases are often somewhat undercut + smaller than the column as a whole, but where unweathered generally expand some- what like the base of a tree, but were not observed to pass out into root-like projections. In places the bases were observed to pass into a fairly continuous hard layer of ss. In some, but apparently not in all, cases the apex reaches and blends with a hard capping. The bed in which they occur generally has such a capping, even beyond the area in which the pillars occur. Weathering does not produce them, but only releases them from the matrix. The apices and often the columns as well are commonly traversed by very steeply inclined fissures with the surface somewhatlike slickensides, but along which very little motion can have taken place. In one or two places irregular low wall-like projections weather out similarly like very irregular dikes. p. 148.