Geverik Member

Formal (Van Adrichem Boogaert & Kouwe 1995).
Lithological description

Interval of dark-grey or black, bituminous, shaly claystones, with abundant intercalated laminae of graded siltstone and very fine-grained sandstone. In the type section, dark-grey to black limestone laminae are intercalated in the basal part. The tops of individual beds are frequently silicified. Tuffaceous bands of cm- to mm-thickness can occur. Because of its high uranium- and thorium-content, the unit stands out prominently on GR-logs (300-500 API units).

Depositional setting

Settled from suspension in an anoxic marine basin with restricted circulation. Low clastic sedimentation rates and distal turbidites.

Definition of lower boundary

In the type section a gradual transition can be observed from the limestone-shale alternation of the Carboniferous Limestone Group into the marly basal interval of the Geverik Member. Elsewhere, the member is usually found to rest unconformably on massive Mississippian (Dinantian) carbonates.

Definition of upper boundary

The ‘hot shales’ pass upwards into the non-bituminous, dark-coloured mudstones of the Epen Formation. The upper boundary is defined by the disappearance of the bituminous character, reflected by an abrupt upward shift to lower GR-log readings.

Thickness indication
Up to 223 m.
Geographical distribution
Regional correlation
UK: Bowland and Edale Shale Formations; GER: Upper Alum Shale Formation; BEL: Souvre Formation.
Serpukhovian - Bashkirian.
Depth (thickness) AH:
926 - 992 m (66 m)
Origin of name
Named after the village of Geverik in the south of the Dutch province of Limburg, where the type section is situated.
Previous name(s)
Reviewed by (date)
Tom van Hoof (2017).
Van Adrichem Boogaert, H.A. & Kouwe, W.F.P. 1995. Stratigraphic nomenclature of The Netherlands, revision and update by RGD and NOGEPA, Section C, Silesian. Mededelingen Rijks Geologische Dienst, 50, 1-40.
Cite as
TNO-GDN ([YEAR]). Geverik Member. In: Stratigraphic Nomenclature of the Netherlands, TNO – Geological Survey of the Netherlands. Accessed on [DATE] from