Revleivs — American Geological Surveys. 179 



constructed from outcrops and borings along tlie line of the Terre 

 Haute and Indianopolis Eailroad, upon which, are shown the positions 

 of the various coals (five in number) and strata, the latter com- 

 prising the Coal-measures, Millstone-grit, Sub -Carboniferous Lime- 

 stone, Shale, and Sandstone ; the Marcellus Shale, and Devonian and 

 Upper Silurian Eocks, and also the levels at which springs of oil or 

 of fresh, salt, and sulphur waters have been proved to occur. 



The first object on commencing the Survey of the State was to ac- 

 quire a more extended knowledge of the Brazil, or Iron-smelting 

 Coal, about which much misconception appeared to prevail ; the 

 general impression being that this peculiar variety of coal, familiarly 

 known as '' Block Coal," or "Brazil Coal," was confined to a small 

 basin, isolated from the great bituminous Coal-fields of Indiana and 

 Illinois, and limited to an area of a few square miles. The Survey 

 of Clay and Greene Counties, though confessedly not made so com- 

 plete as desirable, has established the fact that splint or block coal 

 has been traced from the southern limits of Greene County to Warren 

 County on the north : and, also, that the area of the Indiana Coal-field 

 may be stated at 6,500 square miles, or one-fifth the area of the 

 entire State. According to Professor Cox, his investigations tend to 

 prove that it is only around the edge or margin of the western Coal- 

 basin that thick beds of Coal are to be looked for. Towards the 

 central part of the basin, the Coal-beds which surround it are either 

 altogether absent, or have dwindled down to seams that are only a few 

 inches thick, their places being occupied by a preponderance of Argil- 

 laceous Shale, some Sandstone, and an occasional stratum of Limestone. 



The great depository of limonite Iron-ore is at the base of the 

 Millstone-grit, not only in Indiana, but likewise in Ohio, Kentucky, 

 Tennessee, Illinois, Missouri, Arkansas, and the territory of New 

 Mexico. In Clay county more or less Iron-ore is met with in the 

 Shales all along the outcrop of the Millstone-grit, but as yet it has not 

 been found in sufficient quantity to supply a blast furnace. The 

 common horizon of Iron-ore in Greene Couuty, as in most of the 

 Western States of America, lies at the junction of the Conglomerate 

 with the Sub-Carboniferous Limestone, filling pockets of various 

 dimensions. 



The duties of the State Geologist are sufficiently onerous, for 

 besides conducting the purely Geological Survey, to make known the 

 mineral resources of the State, the law places the State Geologist 

 at the head of a geological and scientific department, for the pui'pose 

 of collecting information designed to promote the interests of Agricul- 

 ture, the Arts, Manufactures, and Mining. The State Geologist is 

 also required to establish a laboratory at Indianopolis, fitted up with 

 all necessary appliances for the analysis of such ores and substances 

 as may be considered likely to be useful to the State ; also, to form 

 Geological and Natural History Collections, and to publish the re- 

 sults of his labours in the Annual Eeports of the Indiana State Board 

 of Agriculture. The analyses of Coals, Iron-ores and Slag, filling 

 two pages (136 and 137), show that this part of the subject has not 

 been neglected. 



