Brintoii.] 



440 



[Nov. 18, 



Vertical section, 21 feet in depth, of a Quarry on Lake Managua, showing 

 strata overlying human footprints. 



1. Surface soil, about 18 inches. 



2. Compact tufa, 20 inches, separated from No. 3, by a sand 



seam. 



3. Compact tufa, 20 inches, separated from No. 4 by a sand 



seam. 



4. Compact tufa, 17 inches, separated from No. 5 by a sand 



seam. 



5. Compact buikling tufa, 28 inches, resting on a seam of 



bUxck sand. 



6. Solid, daik-blue ash, 14 inches. 



7. Hard clay, 12 or more inches, its surface presenting nume- 



rous leav^es (impressions, fossils), and remains of the 

 mastodon. 



8. Pumice, about two inches, unequally distributed. 



9. Sand drift, supporting the clay. 



10. Compact building tufa, 47 inches, separated from No. 11 

 by a sand seam. 



11. Compact tufa, 5 to 7 inches. 



12. Black sand, 1 inch. 



13. Dark, friable tufa, 2 inches. 



14. Volcanic sand, containing fossil leaves, 1 inch. 



15. The dotted line shows the horizon of the foot- 



prints impressed upon number 



16. Compact building tufa, 47 inches. 



17. Yellow sand, believed to be Eocene (?) of undetermined 

 thickness, containing numerous small shells. 



