70 BUIJ^ETIN 109, UNITED STATES NATIOKAI. MUSEUM. 



The Paleozoic rocks of the State, especiall}^ the upper and lower 

 Carboniferous formations, proved to be exceedingly rich in fossil 

 remains, and the whole of the second and a portion of each suc- 

 ceeding volume of tlie reports was devoted to the description and 

 illustration of the new forms discovered in the prosecution of the 

 work of tlie survey. One himdl'ed and ninety-five octavo plates and 

 numerous woodcuts v,'ere required to properly illustrate the species 

 described in the first six volumes. 



The editions of the various reports were exhausted in a few months 

 after publication, and as there was a continued demand for them at 

 the office of the secretary of state, the thirty-first general assembly 

 passed an act in 1881 authorizing a reprint in three volumes of the 

 economical portion of the six volumes previously published, and also 

 requiring the curator of the museum to prepare and publish another 

 volume of geology and paleontology to correspond in form and style 

 with the six originals, to be entitled : Volume 7 of the Geological 

 Survey of Illinois. Five thousand copies of this volume were au- 

 thorized and 3,000 copies each of the three volumes of economic geol- 

 ogy. These three volumes were issued in 1882, and volume 7, con- 

 taining 31 plates, the following year. 



Tlie pviblications of the survey were distributed partly by the gen- 

 eral assembly, each member receiving five copies, and the remainder 

 by the secretary of state, except 300 copies, which were given to the 

 authors of the work for foreign distribution. 



Benefits. — 'The material results of the survey of Illinois have been 

 the correct determination of the coal resources of the State, by de- 

 fining the extent, number, and thickness of the different coal seams; 

 a full report on the lead regions of both the northern and southern 

 part of the State; also pointing out the location and extent of other 

 mineral products, such as building stone, hydraulic, and common 

 limestones, clays for pottery, firebrick, paint, etc. Its contributions 

 to science have been the discovery, description, and illustration of 

 nearly 1,200 new or little known species of fossils and the publica- 

 tion of a geological map of the State on a scale of 6 miles to the inch. 



The development of the coal resources undoubtedly gave a decided 

 impetus to nearly all industrial interests, and in consequence of the 

 cheap and abundant fuel resources, steel and iron mills and extensive 

 zinc works have been established. The same cause has stimulated 

 railroad enterprise and added vastly to the value of the prairie lands 

 which, before the coal resources Avere knov.n, were considered as of 

 little value, in consequence of the scarcity of fuel. 



As noted in the laws, the survey was abolished in 1872, though ap- 

 propriations for completing the publications were continued until 



