224 J. C. BRAXXER OUTLIXES OF THE GEOLOGY OF BRAZIL 



west, belongs to the Federal Union, and the ievr titles relating to that 

 island are given under Eio de Janeiro, in which the federal district is 

 also located. 



ACRE 



Previous investigations. — Our knowledge of the geology of the terri- 

 tory of Acre is derived almost exclusively from the notes of William' 

 Chandless, given in his account of explorations of the upper Purus and 

 the Aquiry. A little sidelight may be had on the geology from the notes 

 of Evans, Church, Keller, and Euzebio de Oliveira on the geology of the 

 falls of the Madeira Eiver. An important contribution is the discussion 

 by Giirich of the age of the deposits along the upper reaches of the Purus. 

 Those beds had been referred by Agassiz to the Cretaceous, but Giirich 

 shows conclusively that they are late Tertiary. 



General geology. — TVith the possible exception of the foothills in the 

 western and southwestern parts of the territory, its entire area is covered 

 by late Tertiary deposits — mostly undisturbed sands and clays through 

 which wind sluggish streams. The entire area is covered by dense forests 

 and there are no roads. The population is sparse and all travel is by 

 water. 



There is no doubt about there being wide zones of alluvial deposits 

 along the larger streams, but there is very httle or no available informa- 

 tion on the subject. 



In the southwestern corner of the territory the frontier seems to be in 

 the foothills of the Andes, but nothing is known of the ages of those 

 rocks, and that area is therefore left blank on the map. 



Economic geology. — Nothing trustworthy has been published on the 

 mineral resources of Acre territory. Gold has been reported from some 

 of the streams heading in the hilly regions in the west and southwest. 



Bibliography of the Geology of Acre 



W. Chandi^ss : Ascent of the River Purus. Journal of the Royal Geograph- 

 ical Society, volume XXXVI. pages S6-11S. London. 1866. 



W. Chandless : Notes on the River Aquiry, the principal affluent of the River 

 Purus. Journal of the Royal Geographical Society, volume XXXVI, pages 

 119-128. London. 1866. Abstract in Proceedings of the Royal Geographical 

 Society, volume XL 1866-7, pages 100-102. 



W. Chandless : Apontamento sobre o Rio Aquiry, affluente do Rio Purus. 

 Annexe (lettra n^ ao Relatorio do Ministro de Agricultura. etc., pages 

 1-6! Rio de Janeiro, 1866. 



W. Chandless : Notes of a journey up the River Jurua. Journal of the Royal 

 Geographical Society, volume XXXIX, pages 296-311. London, 1869. 



George Eael Church: The route 'to Bolivia via the River Amazon. 8°, 216 

 pages, London, 1877. 



