38 
THE CONDOR 
VOL. VII 
is one of the very “facts" about which the geomorphists are now holding the most 
diverging views. Let me quote a few sentences from a paper by Dr. J. W. Spen- 
cer as late as May, 1898: “It would thus appear that these regions (West Indian 
region) stood from ten thousand to twelve thousand feet, or in some localities four- 
teen thousand feet, higher than now;” and further on: “The time of greatest eleva- 
tion and development of the West Indian continent was during the early Pleisto- 
cene period.’’ This brings us surely to the time of the origin of bird migration, 
//conditions were as Prof. Spencer thinks, there is no impossibility of the pro- 
thonotary warblers’ migration route, no matter how it lies across the Gulf of Mex- 
ico, indicating the way by which they originally immigrated into the United States. 
Now, Prof. Cooke will probably answer that there are geologists who hold 
quite opposite views and that he sides with them, because if they are right, it 
would be easy to “refute” Palmen’s theory. But would it? Prof. Cooke speaks 
of the “central portion” of the Gulf as being involved. There is no necessity for 
such an assumption, however. Do away with an elevation of twelve thousand feet 
and let us be satisfied with 100 fathoms! 0 ' Take any map showing the 100 fathom 
contour in the Gulf of Mexico and the drowned valleys from the Mississippi to 
the Tampa, audit will be found that the whole distance from land to land, if it 
were raised up to this level, would be 183 miles! Now draw a hypothetical mi- 
gration route from the northeastern corner of the thus enlarged Yucatan (Cam- 
peche Bank) northeasterly until it strikes the westwardly extended Florida, and 
let this line proceed in a northerly to northwesterly direction along the 100 fathom 
curve to the mouth of the Mississippi sending offside routes up the drowned valley 
of the Tampa, Suwanee, Appalachicola and other rivers, and you have a route 
which would explain many features of the migration of the prothonotary warbler, 
which now are mysterious, and at the same time indicate the way by which it may 
have originally immigrated into the United States. 
It would have been very interesting to have gone into these questions in greater 
detail, but, unfortunately, time and space are limited. All I wanted to show is 
that Palmen’s theory cannot be disposed of in this off-hand manner. To stop the 
error from making further headway in this country will require weightier argu- 
ments than those I have tried to meet today. 
Wash ington , D. C., Jan. 23, 1903. 
c It must be distinctly understood that this quotation of Dr. Spencer’s views does not indicate my adoption 
of them, 
d An elevation of 600 feet is necessary to bring the 100 fathom line on the west side of Florida up to the present 
sea-level, if the rise is supposed to be horizontal. Dr. W. H. Dali has indicated, however, that the last rise of the 
peninsula (subsequent to the one I refer to) “elevated the Atlantic border with its reefs more than the gulf shores.’’ 
In case of such a tilting it will be sufficient for my purpose to assume a mean elevation of less than 200 feet in orderto 
insure a shore line 140 to 150 miles west of the present one during that period of the Pleistocene when “the rhino- 
ceros, the wild horse, the llama, the Columbian elephant, the mastodon, the glyptodon, and various enormous tor. 
toises wandered along the shores of the lakes and through the marshes (of Florida) while the sabre-toothed tiger 
lay in wait.” Surely, the landscape suggested by this quotation might well invite the invasion of the prothonotary 
warbler in the United States! 
