File:The Quarterly journal of the Geological Society of London (12645119373).jpg

1848..
SHARPE ON THE GEOLOGY OF OPORTO.
1-45
Gneiss.
Micaceous schist.
(B.) Lower Silurian Formation.
The series of crystalline rocks
just described is overlaid on its
eastern flank by a band of rocks of
sedimentary origin, of which clay-
slate is the principal feature. This
band of slates commences northward
on the coast near Esposende, about
thirty miles north of Oporto, from
which place it runs to the S.S.E.,
meeting the Douro at Jeremunde,
about twelve miles above Oporto ;
here it crosses the Douro and con-
tinues to the southward, where I
have not followed it.
On the north of the Douro the
band in question varies from four
to eight miles wide, being bounded
eastward by granite and sienite,
which form the greater part of the
province of Entre Minho e Douro.
The most interesting part of its
course is to the south of Vallongo,
from which place to the Douro the
slates overlie a carbonaceous de-
posit containing several beds of
anthracite, which have long been
worked at the village of San Pedro
de Cova, about eight miles E.N.E.
of Oporto, and two miles S.S.W. of
Vallongo, and five miles north of
the Douro.
Sea.
o
.
•J
.
o
o
P
o
Foz.
(a.) Vallongo Section.
The slate formation is developed
on a larger scale at this part than
it is farther to the north : the Ama-
rante road traverses the formation
from its eastern boundary near
Baltar, where it abuts against sie-
nite, and crosses the beds in a de-
scending order from E.N.E. to
W.S.W. : this is nearly the line of
this section, fig. 2. The series is as
follows in descending order : —
1. Micaceous sandstone usually
of a yellowish colour, with some
beds near its base of grey carbona-
ceous sandstone ; usual dip E.N.E.
o
•Si
o
OX
Micaceous schist.
Gneiss.
Micaceous schist.
Chloritic schist.
Coal.
Carbonaceous".
shales and . Ferns.
sandstones. J
Orthis, Trilobites, &c.
San Pedro
da Cova.
y^!& Vallongo.
Ponte
Ferreira,
Carbonaceous
shales, &c. \A
A