The Quarterly journal of the Geological Society of London (12895008833)

212

PROCEEDINGS
OF
THE
GEOLOGICAL
SOCIETY.
.Mar.
9,

M.
Hebert*
also
points
out
in
a
striking
manner
the
variable

nature
of
the
Jurassic
rocks
of
France,
from
the
frequent
oscillations

then
affecting
the
north
of
that
empire.
In
the
Grindelwaldt

(Switzerland),
and
in
large
areas
around,
M.
Escher
von
der
Linth

found
Jurassic
beds
superposed
directly
on
granite
and
subcrystal-

line
rocks.
In
the
Valley
of
St.
Ortee
Mannee,
and
at
Perdas
de

Fogue
(Isle
of
Sardinia),
a
magnesian
limestone
(Jurassic)
covers

horizontally
carbonaceous
shales,
which,
in
their
turn,
rest
on

Lower
Silurian,
and
thus
indicate
two
separate
and
large
blanks.

We
miss
Lias,
Trias,
Permian,
Devonian,
&c.
J


and
I
infer,
among

other
things,
that
a
Carboniferous
basin
laid
long
bare
to
the
sky



but
not
without
effect,
as
we
shall
see.

In
the
South
of
France,
M.
Fournet§
met
with
Oxford
Clay

resting
on
Trias,
near
Valence,
and
likewise
near
St.
Ambroux.

In
Poland,
Oolite
is
incumbent
on
Muschelkalk,
and
the
sand-

stone
of
its
third
stage
on
both
porphyry
and

melaphyr