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Hull Formation
Stratigraphic label: [ordm]hul
Map symbol: Omhul

First published: 14 June 2019
Last modified:

 

 

 

  DISCLAIMER: This English version is translated from the original French. In case of any discrepancy, the French version shall prevail. 

Informal subdivision(s)
Numbering does not necessarily reflect the stratigraphic position.
 
None
 
Author: Raymond, 1914
Age: Middle Ordovician
Stratotype: None
Type area: Gatineau area (NTS sheet 31G05)
Geological province: St. Lawrence Platform
Geological subdivision: St. Lawrence Lowlands Platform
Lithology: Limestone with shale partings
Category: Lithostratigraphic
Rank: Formation
Status: Formal
Use: Active

Background

The Hull Formation, formerly « Hull limestone or Hull beds, » was established by Raymond (1914) to name the crinoid zone of the Trenton Group in the Gatineau and Ottawa (Ontario) area. The name refers to the former city of Hull, which is now a borough of the city of Gatineau. In NW New York, Kay (1937) suggested that the “Dalmanella beds” that overlie crinoid beds in the Hull Formation should also be included in the formation. The name “Kirfield” was subsequently used in Ontario to define this same unit.

 

Description

The Hull Formation consists of crinoid limestone and shale partings (Raymond, 1914; Kay, 1937; Young, 1964; Globensky, 1993). According to Young (1964), the Hull Formation, both on the Ontario and Quebec sides, shows a notable decrease in the amount of shale relative to underlying and overlying beds of the Deschambault Formation. Shale intertratifications are relatively minor compared to dense beds of pure crystalline crinoid limestone typical of the Hull Formation.

 

Thickness and distribution

In Quebec, the Hull Formation is located in the Gatineau area (sheet 31G05) where it outcrops over <10 km and is truncated by regional shear faults. It is 10.6 m thick (Globensky, 1993).

 

Dating

None.

Stratigraphic Relationship(s)

The Hull Formation can be partially correlated with the Deschambault Formation (Young, 1964).

Paleontology

The main fossils of this formation are Parastrophina hemiplicata (Hall), Encrinurus cybeliformis Raymond, Hemiarges paulianus (Clark), Bathyurus ingalli Raymond (Raymond, 1914; Young, 1964; Globensky, 1993).

References

 

Publications Available Through SIGÉOM Examine

GLOBENSKY, Y. 1993. LEXIQUE STRATIGRAPHIQUE CANADIEN – VOLUME V-B – REGION DES APPALACHES, DES BASSES-TERRES DU SAINT-LAURENT ET DES ILES DE LA MADELEINE. MRN. DV 91-23, 336 pages.

 

Other Publications

KAY, G.M. 1937. Stratigraphy of the Trenton Group. Geo­logical Society of America Bulletin; volume 48, pages 233-302.

RAYMOND, P.E. 1914. The Trenton Group in Ontario and Quebec. In Summary report of the Geological Survey, Department of Mines, for the calendar year 1912; Geological Survey of Canada, pages 342-350. doi.org/10.4095/104068

YOUNG, F.G. 1964. Petrology of the Deschambault Forma­tion, Trenton Group, St. Lawrence Lowlands of Quebec. Master’s thesis, Université McGill, Montréal. https://escholarship.mcgill.ca/concern/theses/h702q969p

 

20 mai 2020