Geology Reference
In-Depth Information
tant in determining the age and depositional environ-
ment of limestones used for tesserae.
Microfacies types. Because of the difficulties in-
volved in estimating lithological and textural variations
in small mosaic stone samples, microfacies types of
tesserae are usually more strictly defined than micro-
facies types used in geological facies analysis. Com-
parison with outcrop samples may lead to a reduction
in the number of microfacies types of tesserae. These
types may be lumped together, but also subdivided by
additional criteria (e.g. stable isotope composition).
Standard Microfacies Types. Microfacies types can
be summarized into Standard Microfacies that facili-
tate the estimation of carbonates produced in different
depositional environments.
Comparison with outcrop data. Comparison of geo-
logical and paleontological data and the microfacies
inventory of carbonates within a distance of at least 50
kilometers to the mosaic sites with the microfacies types
of the tesserae.
Evaluation of bio- and lithostratigraphic units. As-
sessment of carbonate tesserae to specific geological
time/rock units followed by suggestions of potential
provenance strata.
Discussion of the results with archaeologists. Prov-
enance assessments may satisfy geologists, but archae-
ology colleagues may tell you that your provenance
proposal can not work, because the region where the
mosaic material is believed to have come from was not
accessible to Romans, because Germanic tribes had oc-
cupied the region.
position and fossils, and potential provenance areas
derived from geological data and comparative samples.
Important results are:
• Punians and Romans used different mosaic materi-
als. The Late Punian pavement mosaics ('pavimenta
punica') consisting of mosaic stones or stone fragments
irregularly embedded into a mortar floor) are domi-
nated by only a few limestone types occurring rela-
tively near to the mosaic sites (Pl. 151/4, 5).
• Roman tesserae exhibit a significantly higher diver-
sity of microfacies and limestones types (8 microfacies
types) than Punian mosaics (3 microfacies types). This
reflects the geographically wider extension of quarry-
ing (within a distance of up to about 100 km) and di-
rected exploitation during Roman times.
• Some of the Carthage tesserae were made from off-
cuts of building stones, as indicated by identical micro-
facies types in limestones used for building stones.
• Most of the tesserae used for the sixth century Byz-
antine Rotunda at Damous-el-Karita (Dolenz 2001; Pl.
151/1-3), the largest Christian basilica in North Africa,
correspond in microfacies types and age to limestone
material already used in Roman times.
Roman mosaic in Kraiburg, southern Bavaria, Ger-
many. The polychrome pavement mosaic exhibits black,
gray, white, yellowish, reddish and red colors. The
tesserae consist of limestones, siliciclastics and a few
ceramics. Carbonate mosaic stones exhibit 18 micro-
facies types, sandstones can be attributed to 8 lithotypes.
All the rock types used for the Kraiburg mosaic can be
found in Triassic, Jurassic and Cretaceous sediments
of the Northern Calcareous Alps. The material of co-
eval Roman mosaics in South Bavaria has been inter-
preted as imported from the Salzburg region. This in-
terpretation can not be ruled out, but several criteria
support another interpretation of provenance. Most rock
types also occur in glacial limestone pebbles and boul-
ders transported from the Alps to the mosaic site dur-
ing the Pleistocene and distributed by Holocene river
systems. The tesserae exhibit curved outlines and bent
surfaces, which means they may have been produced
from rounded pebbles. Several microfacies types cor-
respond closely to microfacies of boulders occurring
in river terraces adjacent to Kraiburg. The most inter-
esting result of the case study is that tesserae of a spe-
cific color can represent up to 8 microfacies types that
indicate carbonate rocks of different age and geologi-
cal position.
Microfacies studies of tesserae can be supplemented
by geochemical analysis (e.g. Mampbelli et al. 1988)
and stable isotope data (Bollin and Maggetti 1996;
Flügel and Ch. Flügel 1997).
19.3.2 Mosaic Material: Examples
The following examples (Flügel and Ch. Flügel 1997)
involve simple pavement mosaics consisting of black
and white stones and polychrome mosaics exhibiting
different colors and designs. The main targets of these
investigations were the adaption of microfacies meth-
ods to mosaic studies, the estimation of the contribu-
tion of local, regional, imported and recycled material,
and the evaluation of time trends in the use of different
carbonate materials for tesserae.
Late Punic, Roman and Late Byzantine mosaics from
Carthage near Tunis. Mosaic stones were studied with
regard to microfacies types defined by texture, com-
Late antique mosaics of the Hemmaberg near Glo-
basnitz, southern Carinthia, Austria. The churches of
Roman Iuenna built in the fifth and sixth century AD
Search WWH ::




Custom Search