The Republican journal., 1916-11-16
ANCIENT OCEANS IN NORTHERN
MAINE.

One of the interesting problems that
the geologist is required to solve IN trac-
ing the development or the earth sur
face to it's present form Is that or deter
mining the areas of land and sea during
different ages The story OF the land
and sea is written in the rocks that under
lie the several continents; the geologlst
must decipher it. The abundant remains
of sea animals in regions which are now
far from the sea furnish clear evidence
that gre at changes have taken place on
the earth's surface since the eras in which
these creatures lived. The accurate in
depreciation of this evidence is, however,
slow and difficult, and much information
is still needed before it will be possible
to do more than make tentative paleo-
geographic maps-maps that show
roughly the outlines of ancient continents
and seas-for the whole world, or even
for fairly we'll known areas, Conse-
quently, an especial scientific value is at
tached to any contribution to knowledge
bearing on the correlation of the rock
formations of the different continents
that is, on the Identification of formations
laid down during the same epoch. Such
wide correlations are supported chiefly
by the character of the animal and plant
remains inclosed in the beds, for group
or association of the same types OF living
forms occurred at essentially the same
time in different parts of the world and
from such an occurrence the geologist
can draw valid differences as to ancient
geography. This principle is especially
applicable to sea animals. for the condl-
tons of life are less variable in the sea
than on the land, many sea forms have
wide distribution, and the chances of the
preservation of such forms are much
greater.
Such contribution to the kno Wedge
Of ancient conditions is contained 10 Pro-
fessi9nal Paper SO of the United States
Geological Survey, Department of the
Interior, on the Fauna of the Chapman
sandstone of Maine" by IL. S. Williams
and C. l.. Breger, which discusses the
fossils found in the Chapman sandstone
of Aroostook County, Maine, near Pros
que Isle The fauna described comprises
l27 species and varieties belonging to
various groups of invertebrates and one
fish, and may safely be correlated with
later phase OF the Helderperg fauna,
which lived in very early Devonlan Time
IN eastern North America. and with the
socalled Hercynian fauna OF Europe.
The Chapman fauna is intermediate in
character between these two and thus
forms a link connecting the two cont
nents. 1t contains enough Identical ard
closely related species in common wi h
each of the other taunas to prove that Ii
was approximately contemporaneous
with them, 1t is, furthermore. younger
than the Tile stone fauna, the uppermost
member of the English Si!urian, or the
late Siurian marine fauna of Arlsaig.
Nova Scotia, and hence helps to establish
a common upper boundary for the ST.
lurian rocks on both sides of the Atlantic
Some of the fossils discussed in this paper
were already known, but many are new.
They are described and illustrated in d
manner that makes the paper valuable to
the stratigrapher and paleonto'oglst,
though it is too technical for the layman