64 MB. 0. H. EVAXS OIST THE [Feb. I907, 



4. ^sotes on tlie Raised Beaches of Taltal (Noetheex Chile). 

 By Oswald Haedey Evans, P.Gr.S. (Eead December 5th, 

 1906.) 



It is well known that the coast of Western South America presents, 

 practically throughout its entire length, phenomena usually con- 

 sidered as being evidences of recent elevation, and the researches 

 of Darwin long ago rendered familiar the shell-beds and terraces of 

 Coquimbo, Huasco, Caldera, and other localities on the Chilian sea- 

 board. Between Caldera and Iquique, however, the coast-phenomena 

 have had little more than passing references bestowed upon them, 

 the minor settlements of the Atacama Desert being seldom visited 

 by travellers until of late years. 



At Iquique, Darwin l found shells at a height estimated between 

 150 and 200 feet, and A. d'Orbigny 2 observed recent shells in Cobija 

 at 300 feet above sea-level. David Forbes 3 states that, between 

 Mexillones and Arica, the evidences of elevation above 40 feet are 

 unsatisfactory. 



During a residence of two years at Taltal, I devoted much of my 

 leisure to the study of the geology of the district. In communi- 

 cating the following observations on the raised beaches, I have to 

 mention with regret the entire loss of all my notes and photograpbs 

 and practically the whole of my collection of fossils, in the Valparaiso 

 earthquake of August 16th, 1906. Having, therefore, to depend 

 almost entirely upon memory, I have been careful to confine myself 

 to statements which I know to be correct, but am nevertheless fully 

 conscious of the imperfection of the paper necessarily resulting from 

 the lack of my original notes. 



The town of Taltal, formerly insignificant but becoming daily of 

 more importance as a port for shipping nitrate, is situated at the 

 head of a small bay formed by the rugged hills and reefs of Punta 

 Taltal. It is built partly in the dry bed of a broad river-valley, 

 and partly along a gently-inclined plain that fringes the bays of the 

 coastal ranges far to the northward, running up the broader valleys 

 to a considerable height and distance from the coast. 



"Wherever sections reveal the structure of this plain, it is seen to 

 consist of sand and well-rounded gravel, derived from the harder 

 varieties of the felsitic, porphyritic, and dioritic rocks of the 

 adjacent hills, but containing also, near the mouths of former rivers, 

 a lesser proportion of material derived from farther inland ; and it 

 is mingled with recent shells, sometimes sufficiently numerous to 

 form distinct beds. Isolated well-rounded boulders of great size 

 are common, more especially where the mountains approach the 



1 ' G-eological Observations ' 2nd ed. (1876) chap, is, p. 265. 



2 'Voyage dans l'Amerique Meridionale : Geologie ' 1842, chap, vii, p. 95. 



3 ' On the Geology of Bolivia & Southern Peru ' Quart. Journ. Geol. Soc. 

 vol. xvii (1861) p. 9. 



