pseudohemicranium (Nieszkowski, 1859), both from the Johvi Substage
[Jewesche Schicht] of the Haljala Stage, emphasizing the genal spine that curves strongly rearwards in combination with the deep lateral glabellar furrows, of which the anteriormost rises up vertically from the axial furrow (see Fig.
Heteractinids are represented by five specimens of Astraeospongium patina Roemer, 1861 from the Volkhov to Kunda stages (Bn and Bm, respectively), and Idavere Substage
(CM) (Rhebergen 2007a).
Palynological and megafloral assemblages indicate that this formation is of Asturian-Cantabrian age, with the substage
boundary occurring within Cyclothem 12, about 25 m above the Hub Coal Seam (Zodrow and Cleal 1985; Zodrow 1989a, b; Dolby 1988; Cleal et al.
as the first of their three periods of the occupational choice process, by Super (1990) as the first substage
of his Growth stage, and by Tiedeman (1961) in the first stage of his Anticipation period.
Puura & Viira (1999), introducing the Vihula Substage
for the Cambrian part and the Karepa Substage
for the Ordovician part of the Pakerort Regional Stage, tried to make chronostratigraphy of the interval easier for use.
Starting from the latter study, the section has been included to the Johvi Substage
of the Haljala Stage, or more precisely to the lower part of the Johvi Substage
This interval lies approximately 40 m above the Asturian (formerly Westphalian D)-Cantabrian substage
boundary (Cleal et al.
1) in the argillaceous limestones of the Gryazno Formation (lower Idavere Substage
, Haljala Stage) in the western part of the St.
The first substage
is preparation, which involves initial focusing and consists of two steps.
Chrono- Stage Substage
Chronozone Index Index Defi- logical nition scale of [10.
According to our findings, the event level coincides with the base of the Bairdia aculeata ostracode Zone in the carbonate-siliciclastic rocks of the Sargian Substage
or with the upper boundary of the Eoparafusulina lutugini--Pseudofusulina juresanensis fusulinid Zone in the shallow reef deposits of the Irginian Substage
condenser must have a continuously variable circular aperture diaphragm (A stop) and be capable of true Kohler illumination for the full spectral range of 350 to 950 nm.