November 17, 1893.] 



SCFENCE 



269 



SCIENCE: 



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RECENT DISCOVERIES IN NORTHEASTEEN NIC- 

 ARAGUA: GRANITE HILLS, MOUTONNED 

 RIDGES AND GOLD-CONTAINING 

 LODES OR REEFS, AND 

 LEADS OR PLACER 

 MINES. 



BY J. CEA'mFOBD, EIO W'ANQDE OR COCO, AT SAN BAMON, NICARAGUA. 



DuEiNG the past year, cominencing August, 1892, ten 

 months of nearly continuous exploration have been spent 

 by the author over an area of some 10,000 to 12,000 

 square miles in the uninhabited wilderness and jungle 

 that cover a large part of northeastern Nicaragua, exam- 

 ining the geology, minerology, and flora existing in great 

 attractiveness and variety in that part of the country. 

 Among the numerous interesting features and peculiari- 

 ties discovered or noted that are worthy, from both a 

 scientific and economical point of view, of a more special 

 description than was given of them in mj- paper, '-Hydro- 

 graphic Area of the Rio Waukey, or Coco-Nicaragua," 

 jjublished in Science, in April, 1893, are the following: 



(a) The granite outbursts exposed on the tops of oval- 

 shaped Cerros or mountains, and which also form the 

 Cima del Cerro and longer axis of long, high, mountain 

 ridges. 



(b) The numerous moutonned ridges and lateral and 

 terminal moraines, in series that evidence the former 

 existence of a glacial epoch which covered an area of sev- 

 eral thousand sc^uare miles in Nicaragua with a flow of 

 glacial ice. 



(c) The erosion-sculptured Cerros that intervene be- 

 tween the granite hills and moutonned ridges, composed 

 of debris denuded from both the nearby granite moun- 

 tains and materials from mountain ranges found further 

 to the southward. 



(d) The reefs or lodes (many of them auriferous) and 

 dykes (of diorite) in which auriferous C[uartz veins are 

 discovered piercing the mountains and ridges parallel to 

 the length of the series of the system; and also the Post- 

 Pliocene leads of drifts of gravels and boulders. Gold 

 is found exposed in the banks at sides of streams, 

 that appear to extend through the erosion-sculptured hills 

 near their base, and also the alluvial leads, drifts of gravels, 

 gold, etc., found in the channels of the creeks and in 

 strata in the lower parts of valleys. 



(e) The composition and fertility or non-fertility of the 

 soil and its fitness, in places, for the vigorous growth of 



certain kinds of trees or plants, also the peculiar forma- 

 tion where groves of some kinds of valuable trees were 

 found growing to large dimensions. 



(f) The apparent geological history of the granite hills, 

 dykes, reefs or lodes, moutonned ridges, erosion-formed 

 ridges, and of the leads or placer mines. 



The region in northeastern Nicaragua chosen for 

 description in this paj^er as typical of a few others in that 

 part of the country is a wilderness unoccupied by man'; 

 and although this locality is a part of Nicaragua, neither 

 the government nor the citizens of that country have even 

 a vague conception of its importance and its truly great 

 undeveloped wealth in valuable minerals and metals, 

 timber, and agricultural lands. The centre of this chosen 

 locality is about longitude 85° W. (from Greenwich) and 

 latitude 11'^ N., and embraces the headwaters of Nawa- 

 wass, Wilson, Loccus, Umbra, Waspoopoo, Moorawass, 

 Sangsang and Daka Creeks, and Wassjjook River, con- 

 fluents to Rio Waukey, or Coco River, and also the line of 

 Cerros, about sixty miles long, just south of the Wasspook 

 River. 



The granite masses appear to be in two parallel lines 

 of elevation, but connected together as one mass and com- 

 posed of rock of the same mineral composition, usually 

 amphibole, syenites (with and without quartz), and also 

 protogene and jjlagioclose varieties apjaear most numer- 

 ous. The cooling has permitted the crystallization of the 

 minerals so similarly at about the same depth from the 

 surface (isogeothermal zone) in each line of ridges, as to 

 indicate that the two exposed lines were of the same mass 

 and lowering in temperature at the same rate. The 

 granite has been exposed by erosion, and the hills, also, 

 have been eroded deeply at many places, and the rocks 

 have, at several places observed, become disintegrated 

 and decomposed, in situ, to depths of five uo twenty feet. 

 The exposed granites are in series of spurs and ridges 

 that extend northeastwardly for about ninety miles from 

 the Barbar Mountains (at the southeastern termination of 

 the Matagalpa system of mountains), and form an angle 

 of about 120° with the southeasterly and northwesterly 

 direction of that mountain system, which is composed 

 largely of Archean and Silurian era rocks. 



The northeastern termination of these granite spurs and 

 ridges is near to the confluence of the Rios Wasspook and 

 Wauque, at a distance of about one hundred miles west 

 from the Carribbean Sea, on the eastern coast of Nicara- 

 gua, and about the same distance south from that sea on 

 the northern coast of Nicaragua. The forces causing this 

 upheaval of granite appear also to have fissured the super- 

 imposed and adjacent systems of rocks for many miles^ 

 These fissures are now filled by deposition of minerals 

 and metals from hot solutions, and are now reefs or lodes, 

 containing quartz, gold, metallic ores, and other minerals. 

 Near the northern termination of these granite ridges 

 were found patches, of varying size, of auriferous sands, 

 gravels, clays, and boulders — detritus transported by 

 water from the denuded granite hills and from ranges in 

 the Matagalpa system of mountains. These deposits of 

 detritus increase in size northwardly, until covered north- 

 wardly by the sands and mud composing the delta of the 

 Rio Wauque; and on the west the deposits of detritus 

 were in large quantities, and subsequently have been 

 sculjjtured by erosion into hills and ridges; also found 

 resting in small areas on the granite ridges are boulders 

 in size from a few pounds to over two hundred pounds 

 each, of varieties of bluish glaucophanyte, or hj-pers- 



'Recentlv two or three Latin-Americans have, in a crude way, simulated 

 placer-raining work in one or two of the mineral localities. They appear 

 hopeful and cheerful. 



-It is very difficult, frequently impossible, to trace the extent of the out- 

 cropping of lodes or reefs, and even of dykes, in this wilderness of dense 

 growtli of trees, vines and plants and a deep soil. 



