The Donaldsonville chief. [volume] (Donaldsonville, La.) 1871-current, 1914-02-21
Huge Mud Lumps at Mouth of Mis-
sissippi.

The territory within a mile OF
Two Of each Of the mouths of the
Mississippi is characterized by large
dwellings or upheavals sof tough, blu
lsh-gray clay, to which has been an
piled the name mud Jumps" Many
Of these mud Jumps rise just offshore
and form islands having a surface
extent of an acre or more and a
| height of to 10 feet. but some dc
not reach the water surface. These
mud Jumps, in addition to being oil
| Importance because Of their effect
on the channels Of the Mississippi
river, are also of considerable pure.
ly scientific interest, for their de.
velopment is not inc1uded in the
usual conception of delta growth, and
although several theories have been
advanced. their cause must still be
regarded as uncertain.
To an observer at the mouth Of
the river the idea that the region
is great dumping ground for a
large part of the United States is
most impressive. The land is be-
ing built out into the sea at an ex-
tlmated average rate Of about 800
feet year; in some places the rate
is much more rapid than in others.
In one place in Garden Island Bay
the land appears to have advanced
1000 feet in the spring of 1912.
The mud Jumps are 3commonly 20
to 30 rods broad and stand 30 or 80
feet above the adjacent bottom.
Their growth occupies from a few
hours to several years land is usual
ly Irregular. Generally mud lump
rises in few weeks #or months to
height of 4 or 5 feet.above the sur
face Of the water. Then it remains
quiet and is beaten down by the
waves in the course of a few years.
! Many Of them ssIbsile however. and
some disappear over night. Those
that rise slowly are considerably
worn before they stop growing, while
those that rise more rapidly and in
protected places are capped by
laminated silt having maximum
thickness Of 10 feet.
The stories related by sailors and
pilots concerning the mode of growth
OF the mud Jumps are fairly consist
ent. One man, however, states that
the growth of a mud lump was ac-
companled by a rather loud roar as
It rose above the water, and another
states that he once saw flashes of
light rising from a mud lump, but
these statements are very different
from the great mass of testimony
concerning the Jumps, and it seems
probable they are not based on fact.
Among the most conspicuous and
Impressive features Of the mud
Jumps are the mud springs that are
lctive on many if not all of them.
The discharge from these springs
consists of salt, Watery mud, and gas
in fact, gas escapes. at many places
on the surface of the delta of the
Mississippi, the vents appearing to
De most numerous and largest on and
lear the mud Jumps, though the rate
Of flow rarely, if ever. exceeds
-eW cubic feet an hour. Gas rises
n bubbles in all the mud springs,
though it's rate of issue varies.
1t is considered by some scien-
isis Lnat the mud Jumps are pro-
tuced by seaWard flow Of layers
Of semifluid clay under the land and
the shallow water near the ends of
the passes. The mud Jumps appear
% be the product of flow, because
In no other places have such thick
bodies Of clay been found, and the
fact that they occur almost exclusive
of !,
hat they are most active during
and after times of high water seem
% support this Theory