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Many of the beds of the Upper Cretaceous Group afford excellent materials for construction, for which purpose they are already largely employed in the settled portions of Texas. They are usually very easily wrought, and often combine firmness, beauty, and great durability; hence they are exceedingly valuable for the construction of public works. Some of the most useful varieties have been indicated in the Journal. The rock quarried near San Antonio, Fort Inge, and Fort Clarke, is, on account of its beauty and property of acquiring hardness upon exposure to the atmosphere, peculiarly valuable.

Quicklime.-By burning, an excellent quality of quicklime for mortar can almost always be obtained from the limestone of this formation.

For the construction of macadamized roads upon the Plains this formation will furnish materials in great abundance. In making selections the hard cherty varieties of limestone should always be preferred when they can be readily obtained.

Chalk. -This important article exists in great abundance on the Rio Seco, and is also believed to occur in the neighborhood of Fort Clarke. It is generally much less pure than the foreign article, but may be made to answer many of the purposes for which the latter is employed.

Lithographic Limestone of very fair quality occurs on the Arroyo Pedro. Some examples obtained from that locality are hard, compact, and susceptible of a very good polish, but contain minute veins and crystals of calcite, which would interfere very materially with the usefulness of the rock for lithographic purposes. Others, however, are perfectly homogeneous in texture, possess a light uniform color, and present all the requisites of a good lithographic stone.

Calcareous Marl. - This valuable fertilizer occurs in the greatest abundance throughout almost the entire region occupied by the Upper Cretaceous strata. In many instances it is composed of nearly pure carbonate of lime, existing sometimes in beds thirty or forty feet in thickness. Could means be devised for transporting it to market, it would prove of inestimable value.