78 Scientific Intelligence. 



II. Geology and Minekalogy. 



1. Geological Survey of Georgia. The Paleozoic group. 

 The Geology of ten counties of northwestern Georgia and 

 resources; by J. W. Spencer, state geologist, pp. 406 and one 

 map, Atlanta, Ga. 1893. — The Paleozoic formations of northwest- 

 ern Georgia are described under the following nomenclature, viz : 

 Cambriaa, Oostanaula formation; Ordovician, Knox dolomite, 

 Chicamauga (including Rockmart slate) ; Silurian, Redmountain ; 

 Devonian, Chattanooga Black shales ; Carboniferous, Fort Payne 

 chert, Floyd shales, Mountain limestone and Coal measures. 

 Part II describes the Economic Resources of the Paleozoic group, 

 coal, iron, manganese, bauxite, kaolin and building materials, 

 graphite, etc. The report is a valuable compendium of the local 

 geology of this corner of the state. w. 



2. The Geology of Mexico. — The following maps and charts 

 illustrating the geology of Mexico have been published recently 

 by the Comision geologico Mexicajia, prepared under the direction 

 of Antonio del Costillo, director of the Escuela n. de Ingenieros 

 and of the Comision geologico : — A small geological map of the 

 whole Republic on the scale of 1:10,000,000, entitled Bosquejo 

 de una Carta geologica de Republic Mexicana; a map on a scale 

 of 1 : 2,000,000, on which the distribution of the following min- 

 erals is shown, viz: gold, platinum, mercury, copper, iron, lead, 

 bismuth, zinc, antimony, coal, sulphur, kaolin, lignite. Carta 

 los meteritos de Mexico, scale 1 : 10,000,000. Cartes geologi- 

 cas de Pozos Artesianos abiertos en ?a gran Cuenca de Mex- 

 ico. Plans of the Penon de los Bafios, scale -£-q\jv' °f tne 

 mining regions of S. Antonio and Triumfo in lower California, 

 scale ,m 001 per 40 ms ; — of the iron mines of Encarnacion and of 

 S. Jose del Oro, scale 1 : 20000, and a detailed plan of the geolog- 

 ical and petrographical structure of the environs of the city of 

 Mexico, scale 1 : 200,000. In the same series appears a large 

 engraving of the geyser in the vicinity of Puebla described by 

 Antonio del Castillo. 



A valuable summary of the present state of knowledge regard- 

 ing the geological formations and their fossils for Mexico is given 

 in Datos para la Geologia de 3£exico, by Jose G. Aquilera 

 and Ezequiel Ordonez of the Escuela de Ingenieros, Mexico, 8vo, 

 87 pp. The following systems are recognized : Archaean, Permo- 

 Carboniferous, a small outcrop near the border of Guatemala, 

 compact limestone with a Productus ? semireticidalus, and certain 

 tracts in the northeastern part of Mexico, which furnish fossil 

 Lamellibranchs, which may be Carboniferous. Triassic, in 

 numerous localities, determined to be upper Triassic. From this 

 system in Ros Bronco in Sonora, Dr. Newberry described a flora 

 of 23 species of plants. The Jurassic system is recognized by a 

 fauna of 37 species distributed among the Sponges, Echinoderms, 

 Vermes, Brachiopods, Lamellibranchiata and Cephalopoda. 



