DISCLAIMER: This English version is translated from the original French. In case of any discrepancy, the French version shall prevail.
|Type area:||Gatineau area (NTS sheet 31G05)|
|Geological province:||St. Lawrence Platform|
|Geological subdivision:||St. Lawrence Lowlands Platform|
|Lithology:||Limestone with shale partings|
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.
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.
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).
The Hull Formation can be partially correlated with the Deschambault Formation (Young, 1964).
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).
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.
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