The Harrison times., 1901-02-16

equivalents as observed in Other
parts of the state, and hence, it has
been no easy task to decide to which
OF the divisions of the calciferous
group certain groups of beds should
be assigned
We now have claimed the geologi
cal scale to Swallows 2nd Magne.
sian Limestone TO lower Silurian age
which, however, included the whole
group as differentiated by Prof. Gala
her as second Calciferous. Moreau,
and Third Calciferous." This leads us
intelligibly into Arkansas where the
exposed mineral bearing rocks are
almost exclusively to this member
and the superimposed ones of the
suhca<hanitsseas-pssiea---It--.hese
fore has an all important interest
for the miner and land owner, more
especially of Marion and Boone
counties, since it is the one wherein
great bodies of zinc ore are known
to exist and, in some locations, lead.
AS surface rock. it spreads out as
marginal area completely surround
ing the 3rd Magnesion limestone
area, and has north and south
prolonga ton that reaches from the
Missouri river on the north, and, to
the south, includes the counties of
Randolph, Sharp, Fulton, lizard and
Baxter, nearly the entire of Marion.
and a good portion of Boone and
Carroll, and the west half of Law
renee. To the south of this, al
though hidden by fragments of the
Subcarbonferous. there is long
margin where it cannot be so very
deep below the surface. We will
endeavor to describe this member as
much as possible in detail.
Its whole thickness embracing
Gallahers group at the ST. Louis
Asylum, is SIT feet; estimated thick
ness in Morgan county, IT'S feet,
and in Ozark county, $50 feet. In
Marion county it in all probability
has thickness of 800 feet.
1t is in the bottom measure of this
group (Gallaher's 2nd Calciferous)
where the familiar cotton rock"
first occurs and continues, in Mis-
souri,, at intervals throughout the
whole group. There, it is not a pure
limestone, but contains argillaceous
,ah so much silica as to al
most entltle 1t to the name OF sand
| stone. Throughout most bf Marion
county, and adjoining, it has been
greatly altered and would scarcely
be recognized as the same rock.
Among the observed fossils are the
Orthoseras, Chemnitzie. Murchison-
ia, Straparollus, a few rrilohites
and a number of Gasterpods. In
Arkansas, where these members
have been metamorphosed and min
eralized the occurrence of fossils is ex-
ceedingly rare, except at times in
their cherts.
The lower member (2nd Calcifer-
ousl, according to Gallaher, is the
deepest exposed one in the White
river basin and is there the surface
rock oyer quite a large area. 1t con-
tains large percentage of silicious
matter, with great quantities Of
ebert, but not nearly so much as the
First Calciferous beneath it. The
character of this 2nd Magnetism
Limestone is more diversified than
that of any other member of either
the Lower Silurian or Cambrian
divisions, except the 1st Magnetism
| Limestone, next above, which in
most respects is very similar. 1t
not only changes decidedly in differ
ent districts, but in the same one i t
consists of strata that individually Y
widely differ in character from each
other, and show that at the time oi
forming there must have been an in.
flow of muddy and silicious matter
| Although where not altered through
heat or chemical and mineralizine
effects the rock has very little com
rnercsc LII,
,t--~.~,ar value, there are places l.
Marion, and also in Boone count,
where the 2nd Magnetism limestone
is almost as hard as granite, anc
even the portions known in Nilsson
ri as cotton rock would never bt
recognized by that name by one who
had never seen it except as occur
ring in portions of that state. The
basal portion of the formation i.
more OF Il compact calcareo-magnes
ian limestone, with beds of sand
stone and ebert intercolated; gener
orally occurring in thicker layers thar
the cotton rock. and often weather.
ing with a rough and jaded surface