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2 Methods
The Berg en Terblijt hardground in the Curfs
quarry was investigated for clues whether or not the hardground
is a normal hardground in comparison to other hardgrounds in IVf7
(see Stratigraphy
of the Curfs quarry). The Curfs stratigraphy was compared to
the top of the Meerssen member in the ENCI quarry. For orientation
in the field, the stratigraphic column of Jagt & Felder, 1996
was used for the Curfs quarry. In the ENCI quarry the Stratigraphic
column of Felder & Bosch, 1998 was used. Detailed stratigraphic
columns were made (scale 1:10) on both locations. All sedimentary
structures, lithology and trends, fossils and other information
were logged on these columns. Samples were taken from every separate
unit; on average every 20 centimeters.
A total number of 73 samples were taken from the
Curfs quarry and 47 from the ENCI quarry. Thin sections were made
from the hard samples. Relative grainsizes and roundness were determined
under a microscope using the samples and thin sections. Also the
hardness and was determined. Grainsize, roundness and hardness was
divided in five relative ranges. Only from larger bioclasts the
roundness was determined.
In the ENCI quarry, it was possible to measure a
complete profile because of the good exposure. Photographs were
used together with fieldsketches to make the profile. The location
of the profile in the ENCI quarry was determined using a GPS device.
Although photographs were made it was not possible to measure a
complete profile in the Curfs quarry. This was the result of recent
algae encrustations, or simply because it was too high above the
quarry floor. Seven sections were measured in this quarry. From
the detailed stratigraphic columns condensed stratigraphic sections
were made. These condensed sections were correlated. In the correlation
of both the Curfs and ENCI quarry, depositionary stages were determined
and described.
From several thick bioclast grit layers, samples
were taken in the Curfs and ENCI quarries (Meerssen member) to compare
the mesofossil contents in general and the Bryozoa content in particular.
In the Curfs quarry the samples were taken from the Caster horizon
and from the bioclast grit layer above the Berg en Terblijt
hardground. In the ENCI quarry, a sample was taken from stage E
in section E3 (see Fig. 4 in 5.4
ENCI Quarry). The bioclast grit layers were dug out and the
material was sieved (diameter of 4 mm). Then the mesofossils were
sorted (over 40 kinds) under a microscope. In the three locations
significant samples were taken; 8000, 2000, and 3000 mesofossils
were sorted.
The Bryozoa were identified by comparing the sorted
samples to collections in Teylers Museum in Haarlem and Naturalis
in Leiden. In the B+T sample from the Curfs quarry, a large percentage
of Bryozoa could not be identified due to encrusting by algae. Free
standing Bryozoa can be massive (solid), foliaceous (sheet-like,
with zooids on both sides), dendroid (branch-like or tree-like),
or fenestrate (many branches joining and rejoining to form a net-like
shape). The massive forms can live in more turbulent water than
the delicate dendroid Bryozoa. To investigate the differences between
the three samples, the most abundant species were arranged
in groups with the same growth form. For this, only species with
an occurrence of at least 2,5% were taken into account. The results
were plotted on a chart.
© 1999
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