508/1. "Sur la Geologie de l'Amazone," by MM. Agassiz and Continho,
"Bull. Soc. Geol. France," Volume XXV., page 685, 1868. See also "A
Journey in Brazil," by Professor and Mrs. Louis Agassiz, Boston, 1868.)
There is a sad want of details. Thus he never mentions whether any of
the blocks are angular, nor whether the embedded rounded boulders, which
cannot all be disintegrated, are scored. Yet how can so experienced an
observer as A. be deceived about lateral and terminal moraines? If there
really were glaciers in the Ceara Mountains, it seems to me one of the
most important facts in the history of the inorganic and organic world
ever observed. Whether true or not, it will be widely believed, and
until finally decided will greatly interfere with future progress
on many points. I have made these remarks in the hope that you will
coincide. If so, do you think it would be possible to persuade some
known man, such as Ramsay, or, what would be far better, some two men,
to go out for a summer trip, which would be in many respects delightful,
for the sole object of observing these phenomena in the Ceara Mountains,
and if possible also near Rio? I would gladly put my name down for 50
pounds in aid of the expense of travelling. Do turn this over in your
mind. I am so very sorry not to have seen you this summer, but for the
last three weeks I have been good for nothing, and have had to stop
almost all work. I hope we may meet in the autumn.

LETTER 509. TO JAMES CROLL. Down, November 24th, 1868.

I have read with the greatest interest the last paper which you have
kindly sent me. (509/1. Croll discussed the power of icebergs as
grinding and striating agents in the latter part of a paper ("On
Geological Time, and the probable Dates of the Glacial and the Upper
Miocene Period") published in the "Philosophical Magazine," Volume
XXXV., page 363, 1868, Volume XXXVI., pages 141, 362, 1868. His
conclusion was that the advocates of the Iceberg theory had formed "too
extravagant notions regarding the potency of floating ice as a striating
agent.") If we are to admit that all the scored rocks throughout the
more level parts of the United States result from true glacier action,
it is a most wonderful conclusion, and you certainly make out a very
strong case; so I suppose I must give up one more cherished belief. But
my object in writing is to trespass on your kindness and ask a question,
which I daresay I could answer for myself by reading