W. M. Gabb—Notes on Costa Rica Geology. 203 
month of hard work, and I had not so much time at my 
disposal. 
Before closing my account of the mountain region, there is 
one other item deserving mention. My instructions required 
me to look for mines, and I examined carefully for traces of 
their colors quite bright. On the beach, at some points, are 
rge deposits of iron sand of great purity, which might be © 
utilized. 
To my great regret, I have not been able to carry my section 
completely across Terraba to the Pacific. On the summit of 
Pico Blanco, after robbing Irazu of its boast that it was the 
only point whence both oceans can be seen at the same time. 
we could only look over Terraba and wish. The granite was 
esse up after the deposition of the Miocene. This I have 
emonstrated by the absence of granitic pebbles in the con- 
glomerate. It therefore seems probable to me, @ priori (I admit 
a not perfectly safe argument), that the same formation ex- 
tended across; and standing on the k, and looking at the 
hills and plains on both sides, I could not but feel convinced 
that on the south base of the mountain I must find the same 
rock as on the north. Add to this, that but a few miles far- 
ther east the rock does actually run around the end of the 
granite, there seems good reason for expecting to find the plains 
of Terraba to be Tertiary. Further, as far north and northwest 
as I have traced sedimentary rocks, they are of the same age, 
ve Moen are broad, flat plains, which sweep around to 
the bases of the volcanic peaks of Turrialba and Irazu, and the 
