Plate 30 





W^^^^^l^'^^ SecT^of^/ 



Location map showing by the dotted belts the distribution of Inwood lime- 

 stone in the Hastings-Yonkers district and the position of the Bryn 

 Mawr tunnel section as well as shaft 13 on the New Croton aqueduct 

 with their relations to the limestone belts. ]\Ianhattan schist and Ford- 

 ham gneiss occupy the rest of the area. 



