416 J.P. Kimball— Geological Relations and Genesis 
may be the seats of long continued drumlin growth. The 
drumlins thus begun will depend less ¢ on the ag aed local 
nee begun, the dieunttis will go on increasing in size, as eae 
as deposition exceeds erosion, always maintaining an arched 
form of least resistance, until a maximum size is reached, or 
until the ice melts away: and in their growth they will 
approach the form to Retied nigh rocky hills would be reduced 
by the reverse process of erosion, if time enough were allowed. 
Under ser iepe glaciation, the whole surface must be rubbed 
down smoot! 
I am well aware that it is venturesome to go so far as this im 
reney: before all the facts are in. When more is known of the 
distribution of drumlins, the suggestions here given may have 
to be abandoned; but it is nevertheless impossible to resist 
theorizing, and perhaps the collection of facts, pro and contra, 
may be hastened by a little venture in speculati on. It is very 
desirable that the regions occupied by drumlins should be 
more closely studied ; “when this is done, it may be possible to- 
ive in more definite terms the reasons for their choice of atti- 
tude, and additional chapters in their history may then be 
written. 
Cambridge, Mass., October, 1884. 
Arr. XLIX.—Geological Relations and Genesis of the Specular 
Iron- Ores of Santiago de Cuba ; by JAmES P. KIMBALL, ' 
For a distance of at least some 20 miles east of the longitude 
of the bay-of Santiago de Cuba, the Sierra Maestra, or “coast- 
range, maintains a height of about 4240 feet, as harometrically 
measured by Mr. Emile Sarlabous, vice French Co nsul, at the 
point on its crest well known as Gran Piedra. On local maps 
of the Province of Santiago, this point is laid down as 5°69 
miles from the coast of the Caribbean Sea, which is generally 
parallel to the crest of the range. The great outlier or escarp- 
ment of Gran Piedra, according to the same authority, presents 
the same lithological foxttites as its lower foot-hills, namely—a 
coarsely crystalline syenyte of eruptive origin. Wherever this: 
has come under my own observation, within the expanse of 
the lower foot-hills, it is penetrated by very numerous dykes 0 
dioryte. 
From the overflow of similar dykes, the upper immediate 
