CHAP. XI. 



On the Thickness of the. 



365 



entire thickness of the great estuarine or Pampean for- 

 mation near Buenos Ayres is nearly 210 feet. 



No. 31. 



Comparative sections of the Artesian "Wells of Barracas and Buenos Ayres. 

 (Distance, 3f miles.) 



Barracas. Kiachuelo. Buenos Ayres. 



Level of equi- 

 librium of 

 the princi- 

 pal spring ) m ^_ | ^_ ± . — •. =^ g High water 



level 



1st. spring . 



2nd spring 



3rd spring 

 4th spring 



N 2nd spring 

 f& 3rd spring 

 ' h 



^t 4th spring 

 lc„ 245 feet 



470 feet 



a. Clays and Tosca . 



b. Sand 



c. Very sandy clay . . . ") 



d. Dark blue plastic clay . . y 



e. Tosca, with calcareous nodules ) 

 /. Yellow sands, very fine and fluid 



Thickness Thickness 

 at Barracas. at Buenos 

 Feet Ayres. Feet 

 — 57 



13 51 



47 



94 



52 



45 



water mark, was 2,658 gallons. Its temperature was 21° Cent., and 

 it had a slightly disagreeable taste, from its being impregnated with 

 salts of lime and magnesia, and a small quantity of sulphuretted 

 hydrogen.' 



