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GEOLOGY.
55
eastern side of Romeleåsen and extending along the boundary of the Rhæt-Lias
region and the Silurian. In most of these strata there occur beds and bosses
or nodules of flint. The strata of the north-eastern chalk region consist partly
of a limestone composed of broken and rolled organic fragments etc. (gravel
limestone or Ignaberga limestone), partly of a finer-grained, almost earthy
limestone (Hanaskog limestone) and partly of quartz-sandstone.
In north-eastern Skåne the Cretaceous has the Archæan as basis, whereas in
other parts of the province it appears to rest upon younger, purely sedimentary
strata, in some places indeed on the Rhæt-Lias Formation. The total thickness
of the Cretaceous is not known with certainty; a deep boring north of Ystad
went down in the Senonian for 500 meters below the surface of the ground
without the basis of the Cretaceous being reached.
Of the fossils found in the older (Senonian) division of the Skåne Cretaceous
we may notice the very abundant Belemnites and a species of ammonite,
Ammonites Stobæi L., which attains a diameter of 40 cm. In the Saltholm
limestone at Annetorp, of the Danian, large numbers of the teeth of some
shark-species have been found. — The Cretaceous rocks have been made the basis
of several industries: common white or blackboard chalk is quarried and worked
up into a finished product at Tullstorp, Kvarnby and Sallerup, east of Malmö;
Saltholm limestone is obtained from large quarries at Limhamn, south-west of
Malmö, and together with clay it forms the raw material for a large-scale
manufacture of Portland cement; the chalky limestones in north-eastern Skåne are
either burnt for lime or crushed to manuring-lime, for use in agriculture as a
fertilizer. — It has been observed that the Cretaceous deposits in north-east
Skåne rest in many places upon a bed of China clay, beneath which the
Archæan bedrock is more or less weathered and disintegrated. These deposits
of China clay yield raw material to some industries in washed China clay and
refractory wares.
From the Tertiary Period, which succeeded the Cretaceous, no
Sedi-mentary strata have been found except at Klagshamn, SAY of Malmö
where, overlying the Coccolite limestone, there has been observed a dark
greyish green glauconite sand or sandy greensand marl, belonging to the
oldest part of the Tertiary, viz. the Palæocene.
During the Tertiary Period the rocks of Skåne suffered very remarkable
dislocations, for it was then that there occurred those great subsidences in the
crust of the earth, along fault-lines running north-west to south-east, that caused
certain Cretaceous areas to be sunk 1 000 meters or more below the level of the
adjacent districts; in conjunction with that vast revolution there happened those
volcanic eruptions whose lava-beds and ashes we see remains of in the scattered
deposits of basalt and basalt-tuff north of Ringsjön in central Skåne.
The present-day tectonic structure of Skåne, the distribution of the various
geological systems, and their conditions of contact, are all due in a large degree
to faults. The direction of the more considerable, perhaps the majority, of these
dislocation-lines is NW—SE, and these have exercised the greatest influence on
the architecture of the bedrock. It is owing to their existence that the geological
systems in Skåne have their peculiar belt-like or zonal distribution; by these
faults the bedrock has been divided up as it were into lengthy zones, some
of which have been lowered more or less beneath the level of others lying
adjacent. There are however other fault-lines intersecting these, and one might
be tempted to compare the bedrock in Skåne to a piece of mosaic-work, the
different "component parts" of which had been in varying degrees dislocated,
chiefly in a vertical direction, some having suffered subsidence, others not.
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