Year: 1872

A Letter from Professor Agassfx-The


Chtltan Glacier TTack-GalapagOs


Islands and the Theory OF Transmuta-


tfon or Specics-The Flora and Fauna


on the Pacific Coast.


on GUATEMALA, July %, 1877.


MY DEAR PIERCE-Do not be surprised at my few
messages. 1t Is about all can do to take advan-
tage OF every opportunity that offers for study and
collecting; but rarely feel sufficiently collected to
do any connected writing. I have another new
chapter concerning glacial phenomena, gathered
during our land journey from Talcahuan0 to San
tiago; but 1t is complicated story that DO not
feel equal now to recording the details In con-
nected statement; while the whole may be put in
few words. There Is broad valley between the
Andes and the coast range the valley Of
Chian extending from the Gulf Of Ancud
or Port Montt to Santiago and farther north
This valley is q continuation, upon somewhat
higher level Of the channels which, from the Strait
OF Magellan to Chloe, separate the islands from the
mainland, with the sole interruption Of Tres
Monies, which gives the clue to the whole, as we
have here In miniature valley between the Andes
and the coast range. Now this great valley, extend


Ing for more than twenty-five degrees OF latitude. Is
continuous glacier bottom showing plainly for It's
whole length the great southern ice sheet has been
moving northwards In 1t. I could find nowhere
any indication that glaciers descending from the
Andes had crossed this valley and reached the
shores OF the Pacific In a few localities only did
notice Andean-f e., vocanic-erratlcs upon the
loose materials filing the old glacier bottom Be-
tween Currillo and Santiago, however, facing the
Gorge of Tenon Isaw two distinct latera moraines,
parallel to one another, chiefly composed Of
volcanic boulders resting upon the old drift and In
dcang by their position The course Of largo glacier
that once poured down from the Andes OF Tenon
IN mi a IN
tending beyond the eastern slope OF the coast
range. These moraines are so well marked that
they are known throughout the country as the Ger
rillos Of Tenon, but nobody suspects their glacial
origin: Even the Geologists Of Santiago assign
scribe in this history St are the @ successive c retrossde ~
steps Of the great Southern Ice eld, that step by
step left to the north OF 1t larger or smaller tracts
OF the valley free OF Ice, that large glacial lakes
could be formed, and In fact, seem always to have
existed along the retreating edge Of the great
that there are everywhere stratihed terraces,
without border barriers (as these were formerly


er @ s as Geg at s soS


upon unstrati1ed drift Of older date, the northern
most of these terraces being the oldest, while those


farther sonth belong to later steps In the waning Of


From these data infer that my suggestion con.
and giaciated G % Surfaces $50 Of the Vicinity % Of Taicahu
ano alluded TO In the postscript Of my last letter,


was much grieved on reaching Valparaiso to
hear OF the mishaps Of the dredging apparatus.
The subsequent departure of Pourtaes has been
great loss to us oil for, Notwithstanding his silent


Our visit to the Galapagos has been. full Of geo.
logical and geological interest. 1t Is most impres.
sve to see extensive archipelago, Of most recent
origin, inhabited by creatures so different from any
known in other parts Of the world. Here we have
positive limit to the length OF time that may be
granted for the transformation of these animals, II
they are In any way derived from others dwelling
In different parts OF the world The Galapagos are
recent that some OF these islands barely
cred with the most scanty vegetation itself pecu
liar to these islands. Some parts OF their surface
entirely bare, and great many Of the crater and
agents have not yet made an impression upon
them. Their age does not, therefore, go back to
carrier geological periods they belong to our time,
habltants come from, animals as well as plants9 II
descended from some other type belonging to some
neghboring land, then 1t does not require such I'M
spcaKably long periods for the transformation OF
species as the modern advocates OF transmutatlon
claim, and the mystery OF change, with hsuch marked
and characteristic differences between existing
Species Is only Increased and brought to q level
with that OF creation. II they arc not autochthones
think that careful observers, In view Of these facts
will have to acknowledge that our science Is not
yet ripe for fair discussion of the origin OF organ


Our stay In Panama has allowed us to make very
extensive collections in the bay and across the
isthmus. was surprised to find so little differ
restriat fauna between tho two oceans. Marked
peculiarities are only to be found among the ma
rine animals and even among them the American
character OF the Atlantic and Pacific marine fauna
is unmistakable We are not surrounded by anil
mails recalling by their peculiarties the many
groups OF islands Of the Pacific ! expect that our
visit to Acapulco will confirm these impressions.


Ysr Professor S !o BENJAMIN PIERCE, superintendent
United Coast Survey.