The Colfax chronicle. [volume] (Colfax, Grant Parish, La.) 1877-1981, 1909-10-23

But, while this is true, it seems
equally certain that during the subsi-
dence of these areas below the sea
level, they existed either as shallow
winter borders of the main continental
areas or as internal seas. For ex-
ample, the great depth of sedimentary
rocks which cover the Mississippi
basin, extending from the Allegheny
mountains to the Rocky mountains,
are shallow-water deposits. So shall
low, indeed. was the water during long
periods that it was little more than
swamp in which the vegetation that
could grow and flourish. But the level
was not constant. After large &C
cumulation of vegetable matter that
could be turned into coal had taken
place, there was a slight and very
gentle sinking of the whole area, so
that mud and sand were brought in
from the neighboring higher lands to
form complete covering for the coal;
so that when 1t was turned into rock
it was able to protect it, and preserve
it for future ages. This process Of
slow but irregular sinking of the Mis-
sissippi basin continued until thou
sands Of feet of sedimentary material
had been washed into 1t, as the Mis-
sissippi is carrying sediment into the
Gulf of Mexico at the present time.
These successive strata. like the
leaves of a book. record the various
| downward movements of the long coal
period. In other countries. especially
In England and China, there is the
same record of long-continued down
ward movements of continental areas
during the coal period
| II this downward movement had
continued always, the coal would
have been inaccessible beneath the
depths of the sea, where, indeed. much
of 1t does still remain. In Nova
Scotia the best seams of coal are
mined many miles and at depth Of
many hundred feet below the bottom
of the sea. In England also some Of
the best seams of coal are followed
out underneath the sea, and 1t is sup
posed that coal veins are continuous
from southern England to the con-
tinent far beneath the bottom of
Dover strait. But fortunately the
downward motion Of the coal area was
In due time arrested, and the contrary
movement begun, which has brought
this priceless material within easy
reach of men In the mountains of
Pennsylvania and China. In the hills
of England and in the plateaux of the
central and western states of Amer
lea. Other illustrations of great
changes in land levels are too
numerous to be mentioned in detail.
In Colorado there was a gradual SUBJ
sidence of land below sea level during
the carboniferous and cretaceons eras
until from 1900 to $4,000 feet Of
sediment had accumulated over the
sinking area But at the end Of that
period the area began to rise, and this
rise has continued until the present
time, when it stands many thousand
feet above the level of the sea-
| SlmlldT WiLueSS 10 SuCn Cudu6cS VI
level is borne by extensive sediment
airy rocks containing abundant sea
shells Of late geological age. which are
found at height Of 10000 feet above
the sea on the Pyrenees, the Alps and
the Caucasus mountains, and at a
height of $4,000 feet upon the noun
tains Of central Asia. A map Of the
eastern continent during the early
part Of the tertiary period shows q
great Mediterranean sea covering all
central Europe and extending into
; Asia, submerging the highlands Of
Thibet and most of the mountains Of
Turkestan. But that this was not .
general subsistence 81 the continents
Ia evident from the simple fact that
these areas are covered with sedimen-
; tary strata. II mud and sand and
, gravel are deposited In water there
must be some area not far away from
which they could be derived.