part 3] THEOUGIt the AISTDES of PEEU and BOLIVIA. 281 



This plutoiiic intrusion, which had its initiation during the 

 post-Jurassic upUft, probably occurred for the greater part during 

 the Tertiary folding of the Andes, when it took the form of a 

 great batholithic invasion of the Cretaceous and older rocks, preceded 

 by and intimately connected Avith a phase of volcanic eruption. 

 At the present d^y an extensive mass of granodiorite, varying but 

 little in character wherever it is exposed, forms a continuous core 

 throughout the whole of the Andes of Central and Southern Peru, 

 over a distance of more than 750 miles, and this must be merely 

 a fragment of its total extent. The subsequent histor}^ of 

 the Cordillera down to the period of human existence comprises 

 many interesting geological problems, the detailed discussion of 

 which Avas beyond the scope of the foregoing paper. Recent move- 

 ments of the strand-line, the former extent of glaciation, and the 

 orio-in of Lake Titicaca, are amons^ those that call for further 

 investigation. 



In conclusion, I feel that, as a visitor to the country about which 

 I have Avritten, I must bear Avitness to the excellent Avork accom- 

 plished by the rapidlv-growing school of geologists in Lima, from 

 Avhom, and especially from their leader Prof. C. I. Lisson, 1 plead 

 for lenient criticism. The geology of this vastly-interesting 

 country is as A^et very imperfectly knoAvn. Many difficult problems 

 remain to be soh^ed, and many errors committed by foreign Avriters, 

 Avhich are the inevitable accompaniment of rapidly-constructed 

 surveys of this nature, stand in need of correction. 



If. hoAA^evei', this series of papers, published as the result of my 

 travels through Peru, acts in any AA^ay as an incentive to further 

 Avork, even though this may lead to contradiction of many of my 

 ATieAvs, I shall feel that, apart from the great gain of personal 

 experience, the late Mr. Balston's generosity in defraying the cost 

 of the expedition has in part been repaid. 



IV. BiBLIOGIlAPHY. 



This list i.s a continuation of, and supplementary to, those published in former 

 papers of this series (see No. 53 infra), to which i-eference may be made for 

 further works dealing with the Geology of Peru. 



(38) 1839. C. L. YON Bitch.—' Petrifications recueillies en Amerique par M. 



Alexandre de Humboldt & par M. Charles Degenhardt.' Secondary 

 Fossils. 



(39) 1851. C. E. Bayle & H. Coquand. — ' Memoire sur les Fossiles Secondaires 



recueillis dans le Chili par M. Ignace Domeyko.' Cretaceous and 

 Jurassic. Mem. Soc. Geol. France, ser. 2, vol. iv, pp. 1-47. 



(40) 1877. W. M. Gabb.— ' Description of a Collection of Fossils, made by Doctor 



Antonio Raimondi in Peru.' Journ. Acad. Nat. Sci. Philad. ser. 2, 

 vol. viii (1874-81) pp. 263-336. 



(41) 1881. GusTAV Steinmann. — ' Zur Kenntniss der Jura & Kreideformation von 



Caracoles (Bolivia).' Neues Jahrb. Beilageband i, p. 239. 



(42) 1881. G. Steinmann. — ' Ueber Tithon & Kreide in den Peruanischen Anden.' 



Neues Jahrb. vol. ii, p. 130. 



(43) 1894. W. MoRiCKE.— 'Yersteinerungen des Lias & rnteroolith von Chile.' 



Neues Jahrb. Beilageband ix, p. 1. 



