Nevertheless, although the phylogeny of the Early Devonian polygnathids has been accepted as the basis for the conodont zonation of the Emsian Stage, this subdivision has been extensively discussed and diverse proposals have been put forward over recent decades (see discussion below and Mawson, 1995 for a historical review).
(1994) proposed a new zonation for the Early Emsian.
Two seismogenic zonations
have been defined, one in a regional scale, and out of it, a national one; therefore, seismogenic zones geometrically fit.
The association between soils and land-use is a type of zonation
, subject to modification according to local conditions and agricultural practice (Table 1) (Barrios 1996).
The chitinozoan zonation
, formally defined for the entire Baltoscandia by Nolvak & Grahn (1993) and later emended by Nolvak (1999), has good correlative value and is widely used in Estonia and elsewhere in Baltoscandia.
Because this technique is a multi-element method, it should be possible to identify similar zonations
for other elements and find intrinsic relationships between different elements.
New data obtained during later studies prompted some modifications of the original zonation
, whereby the scheme became applicable to parts of the northern hemisphere (Marss 1989).
The corresponding unit is included in Mediterranean zonations
(Bizon, 1979; Iaccarino, 1985).
Probable correlations between the Ordovician conodont, chitinozoan, and graptolite zonations
in Estonia can be found in Nolvak et al.
On that account, before worldwide acceptance, there is an urgent need to verify the application of the Baltic conodont zonation
in other areas outside northeastern Europe.
The observation was on aerial mycelium, the colour of substratum, texture, zonation
until the isolate covered the plate.
Therefore, the correlation of shallow water and pelagic conodont zonation
is generally very easy.