CHAP. XI. 



Mammiferous Remains at S.Julian. 345 



the eighth chapter) about seven miles long, and three or 

 four miles wide, estimated at ninety feet in height, and 

 bordered by perpendicular cliffs, of which a section is 

 here represented. 



No. 30. 



Section of the Lowest Plain at Port S. Julian. 

 A A A 



A A. Superficial bed of reddish earth, with the remains of the Macrauchenia, and 



with recent sea-shells on the surface. 

 B. Gravel of porphyritic rocks. 



C and D. Pumicoous mudstone. > . - t tpr +iarv formation 



E and F. Sandstone and argillaceous beds. J AnCient tertiary tormation. 



The lower old tertiary strata (to be described in the 

 next chapter) are covered by the usual gravel bed; 

 and this by an irregular earthy, sometimes sandy mass, 

 seldom more than two or three feet in thickness, except 

 where it fills up furrows or gullies worn not only 

 through the underlying gravel, but even through the 

 upper tertiary beds. This earthy mass is of a pale 

 reddish colour, like the less pure varieties of Pampean 

 mud in Banda Oriental ; it includes small calcareous 

 concretions, like those of tosca-rock but more arena- 

 ceous, and other concretions of a greenish, indurated 

 argillaceous substance : a few pebbles, also, from the 

 underlying gravel-bed are also included in it, and these 

 being occasionally arranged in horizontal lines, show 

 that the mass is of sub-aqueous origin. On the sur- 

 face and embedded in the superficial parts, there are 

 numerous shells, partially retaining their colours, of 

 three or four of the now commonest littoral species. 

 Near the bottom of one deep furrow (represented in 

 the diagram), filled up with this earthy deposit, I 

 found a large part of the skeleton of the Macrauchenia 



