Bowman — Geologic Relations of the Cuzco Remains. 307 



the change from an aggrading to a degrading surface. A 

 buried wall, the subject of another paper,* points in the same 

 direction. Far up the slopes of uninhabited though still cul- 

 tivated spurs one may find these ash beds, and mingled with 

 them are bones of many kinds, shells, charred corn and quina, 

 and bits of broken pottery. Though the relations of this sort 

 of material to the surface in every place indicate that man has 

 long been an inhabitant of the region, no antiquity can be 

 claimed for any of that examined during the work of the 

 present expedition, for it all lies buried in but five or six feet 

 of material. It is, however, equally well stratified and shows 

 that the earliest ash and charcoal material was accumulated 

 while alluviation was still going on. This should not, however, 

 be confused with the strong alluviation of the glacial period. 

 The ash material is interstratified with lower, younger, and 

 thinner alluvium whose lowermost layers may be not more 

 than a few thousand years old. 



Evidences of man's existence in the Central Andes in late 

 glacial or early post-glacial time were reported by the writer 

 several years ago.f From the position of certain abandoned 

 trails and ruined corrals in the Huasco basin and from the 

 nature of associated strand lines and terraces, it is certain that 

 man lived in the region in early times and that he w T as contem- 

 poraneous with a large lake where there are at present only a 

 few scattered ponds and marshes. We have now from the 

 Cuzco basin the actual remains of man found embedded in 

 gravels of still earlier date. The following paragraphs deal 

 with the geologic and geographic character of the gravel beds 

 in point. If their age can be fixed we shall also be able to tell 

 the age of the remains interstratified with them. 



Summary of Results. 



A brief summary of the chief features of the case will serve 

 to guide the reader in his interpretation of the details of the 

 problem. 



The bones found near Cuzco were contemporaneous with the 

 compact gravels in which they were embedded. They were 

 disposed in the form of a lense about 10 feet long and 6 inches 

 thick. From (1) their disposition with respect to each other, 

 (2) their relations with the bedding planes, and (3) their worn 

 condition, it is concluded that they were interstratified with the 

 gravel beds. The age of the beds thus becomes the critical 

 factor in the interpretation. From a detailed study of the 



* A. buried wall at Cuzco : Its climatic significance and its relations to 

 the question of a Pre-Inca Eace. 



f Isaiah Bowman, Man and Climatic Change in South America, Geog. 

 Journ. (London), March, 1909, pp. 268-278. 



