A Rejoinder to Criticisiii on Hypothesis. — Spencer. 113 
of facts and announced my hypothesis,* and since that time 
have added the results to numerous surveys confirming my 
belief that the submarine valleys cutting the continental shelf 
were formed by atmospheric agents. And I hope to revise 
the whole subject, brought down to date, in the near future. 
Dr, Dall in paragraph numbered 2 refers to the work by 
Mr. R. T. Hill, which he says throws "much more light" upon 
the subject.! From the same paper by Mr. Hill I find a con- 
firmation of (a) my previous observations upon the enormous 
amount of denudation of the white limestones since their up- 
lift with moderate dislocation; (b) the subsequent terracing 
(which means both subsidence and re-elevation) high? above 
the present shore line and (c) the remarkable horizontality of 
the late epeirogenic movements. He also shows how the ter- 
races have been incised by gorges and canyons, but he does 
not follow these features below sta-level. However, I could 
not find anywhere that he had thrown any light upon the er- 
ror or extravagance of my hypothesis as may be inferred when 
Dr. Dall says that he has thrown "much more light on the 
subject." That I am right in this contradiction is shown by 
Mr. Hill's own words. He says : "It might be alleged that 
all the ancient topography, shozuing subsidence is still beneath 
the ocean level. . . . The submarine topography hozvever is 
not within the province of this paper." Thus it may be seen 
that Mr. Hill has not studied the very features upon which 
my hypothesis has been based and consequently he is not in a 
position to throw any light upon the subject in any way, yet he 
ventures an opinion thus: "JVitJiout coininitting myself to an 
emphatic negation as yet, I must confess . . . I seriously 
doubt its existence" (that is, late subsidence), and such an un- 
supported opinion Dr. Dall accepts as authority. Xor have I 
been able to find any proof to the contrary furnished by 
j\Ir. Vaughan. 
While speaking of ^Ir. Hill, I shall now improve the oppor- 
tunity of correcting Mr. Hill's measurement of the thickness 
of the Tertiary limestones at Mantanzas (in the Yumuri can- 
• "Reconstruction of the Antillean Continent" by the same, Id., vol. vi, pp. 
103 1+0. Jan.. 1895. 
+ BuU. Miis. Conip. ZooL, vol. xvi, pp. 24-3-288, 1885. Mr. Hill was sent 
to Cuba bj- Prof .\. Agassiz in ISO-t to study the raised coral reefs and 
arrived in Havana just as I was leaving the island. 
t Also: "Geographical Evolution of Cuba" by J. W. Spbncek, BuU. Geol. 
Soc. Am., vol. vii, 1895, sec page 87. 
