von Helmersen started his field studies of the 1838 summer in Keila-Joa and classified the "burning stone" discovered there as graptolitic
argillite which had no industrial value .
3) intracratonic and basinal depression (grey)--relatively deep-water graptolitic
marls and argillites occur in most of the lower part of the Pavilosta core and at the bottom of the Ventspils core.
In Tammekann's opinion, graptolitic
argillite is as soft as glauconitic sand; however, to our mind, this is not correct.
Mafic volcanic rocks, minor tuff, chert, and graptolitic
slate of the Balmoral Group are also present (Wilson 2000b, c).
The Dalmanitina Member, a limestone bed between the graptolitic
shales, may correspond to the second major glacial episode of the Hirnantian glaciations, the mid-Hirnantian glacial episode, equivalent to the stratigraphic position of the Kuanyinchiao Bed in South China in the stratotype section of the Hirnantian Stage.
The distribution of microelements in Tremadoc graptolitic
argillite of Estonia.
Late Early Silurian (Wenlockian) general circulation model--generated upwelling, graptolitic
black shales, and organic-rich source rocks--An accident of plate tectonics?
The studied section starts in laminated siliceous graptolitic
shales of the Oktavites spiralis graptolite Biozone (Horny 1955).
On the geochemistry of postsedimentary mineral formation in the Tremadoc graptolitic
argillites of North Estonia.
In the Ventspils borehole section, a 1 m interlayer of nodular limestone of open shelf origin occurs at this level between basinal graptolitic
argillite and clayey marlstone of the slope facies (Gailite et al.
These samples come from sandstones that have rather low TOC values (less than 1%) and much higher porosities than the surrounding graptolitic
shales, which could make the alternation of carbon isotopic composition of primary organic matter easier.
To illustrate the matter, Table 1 provides fairly full borehole data for a typical Ronneburg, Thuringian graptolitic
shale  and for the Sillamae  and Toolse  uraniferous argillite.