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Texas is abundantly supplied with this material. Not only does it occur in immense deposits in the Permian Beds west of the Abilene-Wichita country, but all through the Timber Belt Beds it is found along the streams and scattered through the clays as crystals of clear selenite, often miscalled "mica" or "isinglass." It is of all degrees of purity, from the pure selenite to an impure gypseous clay. So far it has been little used for this purpose in Texas.

GREENSAND MARL

This marl is a mixture of sand and clay with greensand, and often contains quantities of shells. Greensand, or glauconite as it is often called, is a mineral of green color composed of silica (sand) in chemical combination with iron and potash, and usually contains variable quantities of other substances. This marl also contains more or less phosphoric acid, and the shells furnish lime. Where it occurs in its original and unaltered condition it is of a more or less pronounced green color, due to the color of the greensand in it. Where it has been subjected to chemical action the greensand is gradually decomposed and the iron unites and forms hydrous oxide of iron, or iron rust. This alteration gives rise to a great variety of color in the different beds of the material. When it is fully altered in this way it forms the red or yellow sandstone so much used in East Texas.

Numerous analyses have been made of these marls, both in their original and altered conditions. They contain, in all the samples tested at least, lime, potash, and phosphoric acid, just the elements that are required to fertilize the sandy soils and to renew and increase the fertility of those that have been worn out. These elements occur in the marl in variable amounts, and less in the altered than in the unaltered material. In nearly every instance, however, the amounts were sufficient to be of great agricultural value to every field within hauling distance of such a deposit. It often happens, too, that these beds of marl lie in closest proximity to the very soils on which they are most needed, and all the farmer has to do to secure the desired results is to apply it as a fertilizer.

If any proof is wanted of the adaptability of these marls, and of their great value on just this character of soil, it is shown in New Jersey, where exactly similar conditions exist In that State there were large areas of pine land soils which were, like ours, of little agricultural value because of the small amounts of potash, phosphoric acid, and lime contained