Geology Reference
In-Depth Information
gae and strong biogenic encrustations, and by foramin-
ifera and microproblematica bound to small cryptic
cavities between reef-building organisms. All these
criteria can be found in thin sections made from the
tiny samples of the Iuno head. The identification of
the sculpture material as Late Triassic reef limestone
supports the interpretation of the head as part of a di-
vine sculpture originally located in Iuvavum/Salzburg
(Eingartner and Ch. Flügel 1999).
and Ch. Flügel 1999). The study of thin sections of
four very small samples taken from the back side of
the sculpture prove that the sculpture was made of a
limestone common in the Salzburg area but not in south-
ern Bavaria near Augsburg (Flügel 1999).
Microfacies and fossils are characteristic of Late Tri-
assic reef limestones (Fig. 19.3). The 'Upper Rhaetian
Reef Limestone' is typified by organic frameworks
composed of corals, sponges, solenoporacean red al-
Plate 151 Microfacies and Archaeology: Mosaics, Ceramics and Building Stones
Provenance analysis of stone artefacts, ceramics and ancient buildings is an essential tool of archaeology aiming
for an understanding of ancient life, trade and technology. A number of archaeometric techniques have been
employed comprising microscopic characteristics as well as mineralogical and geochemical criteria. Microfacies
studies can be successfully applied to problems related to source, technological properties as well as the decay
and conservation of carbonate rock materials. The plate illustrates some of the uses of microfacies data in the
investigation of mosaics (-> 1-5), ceramics (-> 6-7) and building stones (-> 8).
1
Mosaic.
Late antique-byzantine mosaic from a subterranean rotunda near the Damous-el-Karita in Carthage (Tunisia), the
largest Christian basilica of Roman North Africa. Sixth century AD. The polychrome mosaic consists of yellowish gray
(bottom row), white (central row), black and dark gray (upper row) and red (brown ochre) pelagic limestones representing
seven microfacies types. Note the differences in texture and microfracture patterns. The material corresponds in microfacies
and the Upper Cretaceous age to material already used in Roman mosaics of the 1st century AD. Thin section. Size of
individual mosaic stones 1.0 to 1.5 cm.
2 Detail of -> 1. Black foraminiferal wackestone with Cretaceous globigerinids. Carthage is flanked by bedded Late Creta-
ceous limestones on the west, south and southeast, at a minimum distance of ten kilometers.
3 Detail of -> 1. Another limestone type used in the mosaic is a black sponge spicula-radiolaria wackestone with fusiform
spicules that may appear as spar-filled circles in cross sections. Larger spheres are radiolarians.
4
Late Punic mosaic
(pavimentum punicum) composed of monochrome white limestone tesserae embedded in a mortar
floor. The limestone used is an echinoderm packstone, probably derived from turbiditic intercalations of shallow-marine
material within Upper Cretaceous pelagic limestones exposed within a distance of about 20 km. Central Carthage. Exca-
vation of the German Archaeological Institute Rome. Thin-section.
5 Detail of -> 4. Echinoderm packstone with the foraminifer
Omphalocyclus
Bronn indicating a Maastrichtian age of the
source rock. Carbonate rocks used in late Punic mosaics and pavements are microfacially less diverse than Roman mosa-
ics. Central Carthage.
6
Ceramic.
Thin-section cut from a sherd of
Punic pottery
. Microfossils (diverse globigerinid foraminifera) and fragments
of crystalline rocks (arrows) are incorporated into the clay matrix. Fossils as well as the mineralogical composition of the
rock fragments indicate that the clays used came from Tertiary sediments of the coastal plains near the ancient city of
Amathus. Good preservation of the calcitic tests of the foraminifera indicates low-temperature firing of the ceramic piece.
Excavation northeast of Limassol, southern Cyprus.
7
Ceramic.
Microfacies analysis of ceramics assists in the search for the area in which the pottery was produced. Fabric and
microfacies of lithic inclusions within the clay matrix can be used in distinguishing local production and imported ceram-
ics, as demonstrated by the Roman
'Auerberg' ceramic
(1st century AD). This ceramic is characterized by marble inclu-
sions (M) whose source area in the Southern Alps was identified by textural and stable isotope data. Marble grains have
been added to the clays in order to improve the quality of the material. Other inclusions are wood and charcoal (CH). The
arrows point to shrinkage structures, indicating low-temperature firing. Lorenzberg near Kempten, southern Germany.
8
Building stone.
The provenance of building stones can be recognized from characteristic geological data, including
microfacies and paleontological criteria. Thin-section studies show that parts of the large wall of the Hittite capital Hattusa
(now Bogazkale) in central Anatolia (14th century BC) were built with limestones derived from local carbonate rocks
outcropping within the area of the ancient city. The rock is a coral bafflestone. Encrusting microfossils indicate an Early
Cretaceous age of the material used as building stones.
-> 1-5: E. Flügel and Ch. Flügel 1997, 8: E. Flügel and Flügel-Kahler 1997
