Clinch Valley news. [volume] (Jeffersonville, Va.) 18??-2019, 1897-04-23
FACTS FROM AN oL6 MAP.
Remarkable showing of Toposraph.
\ &c Chnn1en In Two ccutu-sa.

Remarkable Showing of Topograph-
&c Changes In Two Centuries.
tiswelI known that our Appalachian
mountains werc once very much higher
than the Rocky mountains 81 today;
and that the reason why they are now
comparatively low mountains is simply
that they are very old and have been
worn down by denudatica. The same
destructive influences ure still degrud-
ing them, very slowly as we measure
ordinary time. follower levels. We
know that changes are constantly go
Ing on in the physical condition of the
earth's crust. but these changes are so
slowly accomplished that they can
scarcely be observed, In many cases, in
ian ordinary lifetime. In the coming
ages students of photography will have
a great advantage over those of today;
for the art of accurately delineating the
surface of the earth by means of con-
toured maps Is q comparatively recent
invention. hundreds of years from now
the photographers will be able to
learn from the maps we nre making
now exactly what the surface features
of large areas were in our time, and ID
Vhh VIC Cdog W lu2lhc iHSkTuCklfE COu-
PARSONS with the same features as they
find them.
Prof. Edunrd Bruckner has recently
described in Petermann's Alitteilungen
the very interesting results of COM
parative study of remarkable map OF
the seventeenth century and one of tho
Swiss survey maps of to-day. In 1867
MIR. j. G.. Gyger completed his map Of n
pnrt of the Alpine region extending
from the Rhino on the north to the
Reuss on the south, and including tho
whole of the canton of Zurich, in Swit2-
erland. The map was on an unusually
large scale for that time. The scale was
1892 900, or one inch OH the map for
about half mile in nature. He worked
compass in hand, paced his distances,
and was very careful and laborious in
his survey. He gave great deal of
time for 81 years to his map. He was the
first to use lights and shadows to indi-
cate and contrast mountain slopes. Two
copies of his map. both signed by him,
are eXtnnt, and they still excite the adj
miration of photographers for the Won
derful accuracy with which they de
pict topography. Until this century
the Gyger map was regarded as tho
best photographic delineation of the
Zurich canton. Small parts of it have
been published with corresponding sec
lions of the present surveys, to show
the high standard of accuracy Mr.. Gy-
ger attained.
Mr.. III. Walser has carried out, in the
geographical institute of the University
of Berne, the comparison between tho
Gy ger map and that of the present day.
MIR. Gyger carefully showed every lake,
large and small, in the canton, and sharp
ly distinguished the lakes from swamps
His map showed $40 likes in the canton.
or these no less than 10 arc not found
on the present maps. These lakes, rs
Mr.. Walser points out, one by one, have
become extinct. They were nll small,
most of them having an area of less than
25 acres. The area of IL other lakes is
now much reduced, and 90 others are
somewhat smaller than in the seven
tecnth century. Forty lakes have un-
dergone no important change.
Mr.. Walser has ascertained by obser.
vntion the causes of the shrinkage or
disappearance of 81 of these lakes. Tho
farmers, in their efforts to secure more
meadow lantl, have played an Important
role. They have drained quite mum.
Ler Of the lakes and turned their beds
into hay farms or pasture lands. Oh
course. in geological time, all lakes are
drained by the natural cutting down OF
their outlets, but, on account of the
'nimportant slope OF tho outlet chan
nels of these particular lakes. the deep
ening OF the channels was very slow
and this form of lake cffacement seems
to have cut no figure.
The effects of two other natural
causes, however, arc very evident. One
was the sitting up Of the lakes by the
deposit of sediment, and the other, and
more important, the gradual cncronch
nent of plant life i'll the lakes. which
finally completely filed them, the de-
cay of vegetation forming soil. and thus
the lakes were gradually cxtinguishcd
Some of the lakes are still undergoing
this process, the carpet of plants ex.
tending all around the shores. while
n little water surface is still visible in
the center. The deposition of sediment
and the growth ofplants which finally
obliterated these little lakes were, OF
course, supplemented, as Mr.. Walser
says, by the human activities that, in
the past century. largely cut off the
water supply that made and fed them