GENERAL AND ECONOMIC GEOLOGY 297 



Charles A. White: Contribuigoes a Paleontologia do Brasil (com o original 

 em inglez). Archivos do Museu Nacional, volume VII, 4°, pagiuas 1-273, 

 and 28 plates. Rio de Janeiro, 1887. Three hundred and fifty copies of 

 this report were issued as a special edition, dated Washington, January 21, 

 1888, under the title "Contributions to the paleontology of Brazil; com- 

 prising descriptions of Cretaceous invertebrate fossils, mainly from the 

 provinces of Sergipe, Pernambuco, Para, and Bahia." 



Dr. Geo. H. Whlliams : Description of the rhyolite from Santo Aleixo and 

 Ilhas, Province of Pernambuco. The Cretaceous and Tertiary geology of 

 the Sergipe-Alagoas basin of Brazil, by J. C. Branner. Transactions of 

 the American Philosophical Society, 1889, volume XVI, page 404, footnote. 



Geo. H. Williams : Geology of Fernando de Noronha. Petrography, part II. 

 [For part I, V. Branner.] American Journal of Science, volume CXXXVII, 

 pages 178-189. New Haven, 1889. Abstract of parts I and II in Neues 

 Jahrbuch flir Mineralogie, 1890, volume I, page 85. [Referate.] 



E. Williamson : Geology of Paraiba and Pernambuco gold regions. Trans- 

 actions of the Manchester Geological Society, volume VI, pages 113-122. 

 Sessions of 1886-1887. Manchester, 1868. 



PIAUHT 



Previous investigations. — The map of Piauhy east of Floriano is taken 

 from SmalFs Mappa geologico do Piauhy, published in 1914 by the In- 

 spectoria de Obras contra as Seccas under Dr. M. A. E. Lisboa, while the 

 part west of Floriano is from the map published by Dr. Jose Estacio de 

 Lima Brandao under the Inspectoria Federal das Estradas in 1913. 



' There are two^ important papers on the geology of Piauhy, that of Dr. 

 Lisboa on the Permian geology of northern Brazil, and that of H. L. 

 Small on the "Geologia e agua subterranea de Piauhy e Ceara." Since 

 these papers came out I have received specimens of Psaronius from Eio 

 Parnahyba below Philomena which show the further extension of the 

 Permian in the southern part of the state. The notes of George Gardner, 

 of Spix and Martins, and of J. W. Wells are fragmentary, but useful. 



General geology. — The Archean rocks are exposed in Piauhy only in 

 the southeastern part of the state, where it joins Ceara, Pernambuco, and 

 Bahia, and in a small area near the north end of Serra Grande. 



The oldest sedimentary beds known in the state are those of the Serra 

 Grande, supposed to be of lower Permian age. These rocks are conglom- 

 erates, sandstones, limestones, and calcareous shales. The strata are 

 often false-bedded, and the series has a maximum thickness of 700 meters. 

 The beds dip toward the west or northwest, at an angle of from four to 

 seven degrees. No fossils have been found in the rocks of this group in 

 Piauhy and their age is not certainly known. 



Overlying the Serra Grande series are the Upper Permian sediments, 

 which consist of a series of horizontal, reddish calcareous sandstones and 



