2.50 Ml?. J. A. DOUGLAS OX GEOLOGICAL SECTIONS [vol. Ixxvii, 



in the South of Peru, represented at the present cla}^ hy isolated 

 fragments bounding the shores of the Pacific. Pocks of this 

 nature are said by Prof. Steinmann to extend as far north as Pisco ; 

 but, as the result of observations made during a visit to that locality, 

 1 am led to question the accuracy of such a statement. In the 

 peninsula of Paracas, a few miles south of the port, the rocks on 

 the coast were found to consist of coal-bearing quartzites of Palaeo- 

 zoic age, yielding numerous plant-remains. These beds are over- 

 lain unconformably by marine Tertiary- deposits, pierced by later 

 igneous intrusions ; but I could fmd no trace of the existence of 

 ancient igneous rocks or crj'stalline gneisses such as occur farther 

 south. 



The plutonic rocks met with in the neighbourhood of lea belong- 

 to the gran odiori tic series of the main Cordillera, and are not to be 

 confused with the granitic rocks of the coastal series. The presence 

 of these Carboniferous deposits at Paracas is of considerable 

 interest, for they furnish the only known occurrence of fossiliferous 

 Palaeozoic strata on the Pacific coast of Peru, and, moreover, dis- 

 prove the statement of David Forbes ^ that there is * no example 

 of the occurrence of Carboniferous beds anywhere along the coast 

 of the Pacific in South America.' 



An accurate determination of the age of the flora is, therefore, 

 of great importance, the more so as Prof. A. C. Seward, who has 

 very kindly offered to study the specimens which I collected, has 

 pointed out to me that a list of species previously published by 

 P. Fuchs 2 contains both Wealden and Carboniferous forms. The 

 result of Prof. Seward's research will doubtless show that the 

 determinations of that author were erroneous. 



In the neighbourhood of Lima the zone of Mesozoic rocks 

 extends to the coast, and any continuation of the coastal Cordillera 

 of the south lies submerged beneath the waters of the Pacific. 

 That this fact has not always been hitherto fully recognized is 

 clear from the account given by Eduard Suess^ of this area, 

 of which he remarks 



' we may start from Lima and proceed up the valley of the Eimac . . . (and) 

 we shall first come upon the broad, often gold-producing granite -ridges of 

 the Coast Cordillera.' 



As will be shown later, the ' Andes granite ' of the Lima district 

 is of post- Cretaceous age, and is totally distinct from the ancient 

 granite of the coast in Southern Peru. Nowhere in the sections 

 previous^ described does the Mesozoic zone contribute so largely 

 to the formation of the loft^^ Cordillera as it does along the line of 

 the section now described, where it can be followed more or 

 less continuously from the Pacific coast to the eastern slopes of 

 the range. 



1 Q. J. G. S. vol. xvii (1861) p. 51. 



2 ' Nota sobre el Terreno Carbonifero de Paracas ' Bol. de Minas, 1900, 

 Lima (Peru). 



3 ' The Face of the Earth ' Engl, transl. vol. i (1904) pt. 2, ch. ix, p. 528. 



