142 BULLETIN OF THE 
ciently powerful to break up and pack large shells in the manner 
accomplished by swift moving waters. It is possible that in part the 
growth of the Cincinnati anticlinal took place at a later date, but the 
greater part of its elevation was probably due to Silurian time. It 
seems to me that it can best be explained in the manner above indi- 
cated. It is a noticeable fact, that the Cincinnati axis is most developed 
along the line to the east of which this accumulation in the paleozoic 
seas derived from the bordering land was most extensive. Moreover, 
the general form of the elevation is quite comparable to that of Florida, 
though the axis of position is widely contrasted in the two cases. 
If I am right in my supposition as to the origin of these curious 
reliefs in the region about the Gulf of Mexico, if the anciently developed 
axis of the Mississippi valley, the Floridian peninsula and that of Yuca- 
tan, and the greater islands of the Caribbean, represent the results of 
counter-thrust arising from the imposition of sediments on the sea-floor, 
it is evident that we have in this part of the earth’s surface a remark- 
able exemplification of the effect of weight on the attitude of the crust. 
It must be confessed that the matter is extremely speculative. I should 
hesitate to give it note, were it not for the fact that the whole problem 
as to the effect of weight of sediments is now much under discussion, 
and it appears to me worth while to call attention to this district, where 
there may be something like critical evidence as to the verity of the 
hypothesis. 
The detailed topography of Florida is interesting from the light it 
throws on two important problems, the growth of coral reefs, and recent 
changes in the path of the Gulf Stream. As to the first of these ques- 
tions I have little to add to the considerations which have been brought 
forward by other writers. This little pertains to the distribution of the 
living and the elevated reefs on the eastern shore between the southern 
part of Key Biscayne and St. Augustine. Inside the living reef between 
Key West and the southern part of Biscayne Bay the southern coast of 
Florida is low. From the reports of others it appears likely that there 
are ridges, probably in their nature coral reefs, such as Long Key, at a 
distance of a score or more miles from the swampy border of the land. : 
Near the southern end of Biscayne Bay we find the first distinct reef 
near the shore. This reef comes above the level of the sea about ten 
miles north of Mangrove Point, just to the west of Old Rhodes Key. 
It gradually rises, until at Cocoanut Grove, immediately west of Key 
Biscayne, it has a height of about twenty-two feet and a width of about 
two miles. As the uppermost part of the deposit consists of character- 
a ae 
