Methodology and Techniques - Trace Fossils as Indicators of Sedimentary Environments - page 243

2.5 Building Stones
Building stones are a valuable source for ichnological studies, but as yet, their
potential seems not fully utilized. Of special interest are cases where plenty of
material was cut from a known outcrop, ground, and polished. The stratigraphi-
cal position of the material can often be recognized on the basis of information
known from the outcrop, and the wealth of cut surfaces offers ample details for
investigation. Examples of ichnologically interesting material include slabs of
Mesozoic limestone in Italy ( Fig. 1 E), Cenozoic sandstone slabs with flysch
trace fossils in provincial towns of the Spanish Pyrenees ( Fig. 1 F), and Turonian
sandstone with crustacean burrows from Saxony in Germany used in many his-
torical buildings in Dresden and Berlin ( M¨ ller, 1971 ). Outstanding is the Ordo-
vician limestone from Scandinavia, Baltica, and NW Russia ( Knaust et al.,
2012 ), which was quarried for hundreds of years as an excellent building stone
for St. Petersburg, Stockholm, Copenhagen and many Hanseatic towns to where
it was shipped in the Middle Ages as ship ballast. Building stones of that Ordo-
vician limestone revealed many secrets and assisted Ekdale and Bromley (2001,
2003) in the establishment of new ichnotaxa.
2.6 Quantification of Bioturbation
The quantification of bioturbation provides a clue to the bottom conditions for
the infauna and therefore is essential in ichnological studies. Widely accepted
is the bioturbation scale from Reineck (1963) , which later was revitalized by
Taylor and Goldring (1993) . A similar semiquantitative classification scheme
and visual charts were subsequently introduced by Droser and Bottjer
(1986) , modified by Miller and Smail (1997) to include bioturbation on bedding
planes, by Lockley (1991) for trampling on soil or sedimentary substrates by
dinosaurs (dinoturbation), and by Montague et al. (2010) to estimate the extent
of microbioerosion. An overview of semiquantitative and quantitative methods
was recently given by Marenco and Bottjer (2011) .
The Reineck scale was originally developed for the description of bioturba-
tion observed in box cores from the southern North Sea and ranges from grade
0 (no bioturbation) to 6 (bedding completely destroyed). The degree of biotur-
bation indicates the percentage of bioturbation within a vertical section, for
example, the area that is occupied by bioturbation, and is commonly expressed
as the bioturbation index (BI). This scheme has the great advantage that it has
been widely applied in ichnological studies and thus allows for comparison of
the bioturbation degree in different settings. However, two issues are worth dis-
cussing that influence the applicability of any existing scheme. These are the
scaling issue and the fact of categories having unequal proportions.
Initially, Reineck (1963) implemented his scale for a semiquantification of
biogenically disturbed (bioturbated) sediment, while later on, this method has
been extended in order to include discrete traces and trace fossils. In the latter
respect, there is a scaling relationship between the size of the trace fossils