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existence, within the Coal Measures, of certain areas heretofore untried, in which the mining of coal will undoubtedly be profitable; it has pointed out a source of wealth in the phosphatic marls of certain sections; it has shown that gold may be mined with profit at many points within our limits; it has demonstrated the fact that clays suitable for the manufacture of fine porcelain ware, fire-brick, tiles, and other articles, occur in practically limitless quantity in many sections; it has pointed out the localities where good marbles and building stones may be had for the quarrying; all these have as yet not been turned to account.

Unsolved problems.—Of the problems of geological interest, developed in the course of the survey but not yet settled, I may mention the following: The stratigraphic relations of some of our Lower Cambrian formations are still uncertain; the relations between the formations of unquestioned Cambrian age, and the gold-bearing semi-crystalline strata adjacent to them and in some instances interlocking, are yet to be definitely fixed; the correlation of the seams of our three coal fields is still an unsolved problem, at least in its details.

Work yet to be done.—After the issue of the publications now in hand, the most important items of work proposed, are 1) The accurate mapping of the outcrops of all the coal seams of economic importance. The finishing of two or three of the sheets of the U. S. topographical survey will render this comparatively easy. 2) The preparation of county maps on the scale of half an inch to the mile, with accurate locations of all mineral deposits, mines, etc., as well as of the geological formations. 3) A republication, or rather a new edition, of the Agricultural report, with a map showing the distribution of the soil varieties. 4) An investigation of the water supply of the Coastal plain region, with special reference to Artesian borings. Much of the material for this is already in hand and in part published.