Calcareous Cement at www.japanese-home-gardens.com

Silty deposits: The average diameter of silt-grade grains is from 0.01 to 0.1 of a millimeter. Silts and silt-stones have angular quartz grains and are generally more admixed with argillaceous, calcareous, and ferruginous material than arenaceous rocks. Loess is a wind-blown silt with a calcareous cement.

(5) Portland cement concrete. This is made by mix-ng Portland cement, sand, stone or gravel, and water. Portland cement is produced by mixing together argil-aceous and calcareous materials (such as clay or shale md limestone), heating them to a high temperature, and ;rinding the resulting clinker to a fine powder. (6) Miscellaneous materials. These are blast furnace ilag, seashells, coral rock, caliche (in natural deposits), ind the residue of the spontaneous combustion of waste 'rom lignite coal mines. They are useful in road sur-acing because they do not soften when it rains or break eadily under wheel loads.

Consolidation.—Loose materials are made to cohere by cementation or compaction. In cementation the grains are bound together by cementing substances that have been deposited between the particles. Thus sands may be converted to sandstones by calcareous, ferruginous, siliceous, or argillaceous cements (lime, iron, silica, and clay, respectively).