﻿28 Notices of Memoirs — Prof. C. Wiener — Shell-heaps of Veru. 



is almost entirely decomposed into kaolin. The laminae or strata of 

 the rocks, occasionally of enormous size, and frequently visible in 

 the bed of the river, follow the direction of the West- African schistose 

 group, striking N. — S., and dipping E., with a high angle. The hills 

 on both sides of the Ogowe river do not exceed 300 or 400 meters in 

 height, excepting some few isolated heights estimated at 600 to. 700 

 meters. The plain of the Okande region lies between 150 and 200 

 meters above the sea-level. The hills and the plain are both covered 

 by a yellow, ferruginous, unstratified loam, without traces of organic 

 remains, but containing concretions of argillaceous hydroxyd of 

 iron and layers of soft white marls. 



Innumerable erratic blocks of granite are spread over the hills 

 and the plains of the Okande region. They have been transported 

 and deposited there by the waters of the Ogowe, which was far 

 more extended during the Diluvial Period than at present. A 

 number of Lakes, on both banks of the Ogowe, and only separated 

 from it by a strip of ferruginous loam, are the remains of the 

 former extension of this river. 



The whole region between the estuary of the Gaboon and the 

 delta of Kamma (N'comi) may be regarded as having been under 

 water previous to the deposition of these loams. The waters, sub- 

 siding into the valleys, formed rivers, and the more or less marshy 

 tracts of land were gradually covered with the present immense 

 virgin forests, obstacles to the investigation of the interior and 

 breeding-places of deleterious miasmata. 



IV. — Notes on Shell-heaps on the Coast of Peru, South America. 

 By Prof C. Wiener. (From the Journ. Imper. Geograph. Soc. 

 Vienna, 1876, pp. 486-9.) 



[Commimicated by Count Marschall, C.M.G.S., etc.] 



OF these Shell-heaps, or "Sambaquis," some lie along the coast, 

 others 18 to 20 miles inland. They consist of accumulations 

 of either whole or broken shells of a Venus, a large Ostrea (now 

 living in brackish water), and Corbulce. Some of these mounds are 

 60 meters high, and 100 meters in diameter. 



Those composed of fragments are marine beach-deposits, and mark 

 the course of the ancient coast-line. These are generally seA^eral 

 kilometers in length, and their height does not exceed 1^ meter. 

 The gradual upheaval of the Peruvian Coast being an undoubted 

 fact, the age of these natural accumulations must be admitted to 

 stand in direct proportion to their distance from the present coast. 

 In fact, two of those most remote from the shore are composed of a 

 species of Corbula no longer living on that coast. Prof. Wiener 

 concludes, from the results of his measurements, that about fifty 

 years ago, the whole Ratone Valley was under water, and that it has 

 risen half a meter during the last ten years. The " Sambaquis " 

 have escaped atmospheric disintegration, both by a crust (occasion- 

 ally in the large mounds 40 meters thick), due to the dissolving 

 action of carbonic acid and ammonia in the rain-water, and by a 

 luxuriant vegetation. 



