Type Locality:

Bell (1929) did not designate a type locality, but the type area is the south flank of the Gaspereau Valley and the Horton Bluff area, Kings County, Nova Scotia (NTS 21 H/1).

Distribution:

Based on seismic data, Martel (1990) determined that Horton Group strata thicken markedly between the Noel No. 1 well and the Cobequid-Chedabucto fault zone. Good sections are exposed along north flowing brooks, especially Harding, Curry and Rupert brooks, Hurd Creek, and at Horton Bluff. In the type area near Hantsport on the west side of the Avon River, the Horton Bluff Formation is at least 525 m thick (Martel and Gibling, 1996). A maximum value of plus or minus 730 m is derived from adding together the thicknesses of the four members. To the southwest in the Falmouth area, the Horton Bluff thins to 350 m and pinches out in the Five Mile Plains area, southeast of Windsor. In the subsurface, the formation is 1015 m thick in the Soquip Noel No. 1 well at Kennetcook.

Lithology:

Fluvio-lacustrine, predominantly grey to black, very fine- to very coarse-grained clastics (shale to conglomerate), commonly sublitharenites to orthoquartzites; feldspar is commonly altered to kaolinite; usually quartz rich. The Horton Bluff represents a fluvio-lacustrine clastic sequence. Martel and Gibling (1996) recognized four lithostratigraphic intervals, (A), (B), (C), and (D) in the Harding Brook Member. They interpreted the basal breccia (A) as a paleosol. The sandstones of (B) and (C) were deposited by bedload-dominated braided streams, with the mudstones denoting deposition on local floodplains and abandoned channels. Interval (D) sandstones represent proximal delta and distributary channel deposits. Martel and Gibling (1996) interpreted the environment of deposition for the overlying Curry Brook Member to be like that found in Holocene interdistributary lakes and bays of the Mississippi Delta. The third member, the Blue Beach Member, was deposited in a large, wave-dominated lake (Martel and Gibling, 1996). The progradational cycles represent an upward shift from offshore clay shales (facies 1), to nearshore/shoreline sandstones and siltstones (facies 2), to hydromorphic paleosols (facies 3 and 4). The presence of agglutinated foraminifera and ostracods suggests that the lake was, at least some of the time, connected to the ocean, giving rise to a restricted marine environment (Wightman et al., 1994). Martel and Gibling (1996) considered the Hurd Creek to have been deposited in a fluvio-lacustrine environment, with the coarsening-upward cycles reflecting progradation of coastal sediments over offshore sediments. However, there also appear to be sand bar and deltaic distributary-channel deposits. The Hurd Creek Member is approximately equivalent to the upper member of Bell (1929, 1960).

Fossils:

The two most common and characteristic species of plant fossils in the Horton Bluff Formation are Aneimites acadica and Lepidodendropsis corrugata

Relationship:

Belonging to the Horton Group in the type area (The Horton Group includes the Horton Bluff Formation and the Cheverie Formation in the type area. Other formations of the group outcrop in Cape Breton Island (Murray, 1960) and New Brunswick; according to Murray (1960) it includes the Ainslie, Strathlorne and Craignish formations in Cape Breton). The Horton Bluff includes four members which, in ascending order, are: the Harding Brook Member; the Curry Brook Member: the Blue Beach Member; and the Hurd Creek Member. The Horton Bluff Formation is in angular unconformity or fault contact with older basement rocks in the type area such as the Cambrian to Ordovician Meguma Group and Devonian granite; various units of the Horton Bluff Formation may lie in contact with the older rocks. It is disconformably or unconformably overlain by the Cheverie Formation.

History:

The rocks now termed the Horton Bluff Formation were first described by Jackson and Alger (1828, 1829). Bell (1929) named the Horton Bluff as the basal formation of the Horton Series, in which he also included the Cheverie Formation. He subdivided the Horton Bluff into a basal, a middle and an upper member. The Horton Series was renamed the Horton Group by Bell (1960), who redescribed the three members of the Horton Bluff Formation and subdivided the middle member into a lower sandstone and upper shale unit. Worth (1969) was the first to map lithologic units in the formation and renamed the basal, middle and upper members, as the Gaspereau sandstone, the middle sandstone and the upper sandstone, respectively. Like Bell before him, Worth subdivided the middle sandstone into the Curry Brook sandstone facies and the overlying middle shale facies. McDonald (1973) proposed that only the middle member was represented at Blue Beach. Detailed maps of the western part of the Windsor Subbasin were published by Ferguson (1983) and Moore and Ferguson (1986). These authors recognized the lower, middle and upper members, but disagreed with Bell (1960) on the aerial extent of these units. Following a detailed study of the type area, Martel and Gibling (1996) formally erected four members which are, in ascending order: the Harding Brook Member, which is approximately equivalent to the Gaspereau sandstone; the Curry Brook Member, which is approximately equivalent to the Curry Brook sandstone facies of the middle sandstone; the Blue Beach Member, which is equivalent to the middle member or middle sandstone; and the Hurd Creek Member, which is equivalent to the upper member or the upper sandstone. Martel and Gibling (1996) agreed with Bell (1960) that both his middle and upper members outcropped at Blue Beach.

References:

Bell, W.A., 1929. Horton-Windsor district, Nova Scotia; Geological Survey of Canada. Memoir 155, 268 p.

Bell, W.A., 1960. Mississippian Horton Group of type Windsor-Horton District, Nova Scotia; Geological Survey of Canada, Memoir 314, 58 p.

Ferguson, S.A., 1983. Geological map of the Hantsport area, Nova Scotia; Nova Scotia Department of Mines and Energy, Map 83-1, Scale 1:25,000.

Hacquebard, P.A., 1972. The Carboniferous of eastern Canada; Septieme Congres International de Stratigraphie et de Geologie du Carbonifere, Krefeld 1971, Compte Rendu, vol. 1, pp. 69-90.

Jackson, C.T. and Alger, F., 1828. Mineralogy and geology of a part of Nova Scotia; Yale University, American Journal of Science, vol. 14, pp. 305-330.

MacDonald, D.J., 1973. Stratigraphy of the upper member of the Horton Bluff Formation in the area of the type section near Hantsport, Nova Scotia; Unpublished M.Sc. thesis, Acadia University, Wolfville, Nova Scotia, 301 p.

Martel, A.T. 1990: Stratigraphy, fluviolacustrine sedimentology and cyclicity of the Late Devonian/Early Carboniferous Horton Bluff Formation, Nova Scotia, Canada; Ph.D. thesis, Dalhousie University, Halifax, Nova Scotia.

Martel, A.T. and Gibling, M. 1996. Stratigraphy and tectonic history of the Upper Devonian to Lower Carboniferous Horton Bluff Formation, Nova Scotia; Atlantic Geology, vol. 32, no.1, pp. 13-38.

Martel, A.T., McGregor, D.C. and Utting, J., 1993. Stratigraphic significance of Upper Devonian and Lower Carboniferous miospores from the type area of the Horton Group, Nova Scotia; Canadian Journal of Earth Sciences, vol. 30, pp. 1091-1098.

Moore, R.G. and Ferguson, S.A. 1986. Geological map of the Windsor area, Nova Scotia; Nova Scotia Department of Mines and Energy, Map 82-6.

Murray, B.C. 1960. Stratigraphy of the Horton Group in parts of Nova Scotia; Nova Scotia Research Foundation Publication, pp. 1-123.

Playford, G., 1963. Miospores from the Mississippian Horton Group, eastern Canada; Geological Survey of Canada, Bulletin 107, 47 p.

Utting, J. 1987: Palynostratigraphic investigation of the Albert Formation (Lower Carboniferous) of New Brunswick, Canada. Palynology, vol.11, pp. 73-96.

Utting, J., Keppie, J.D. and Giles, P.S. 1989. Palynology and stratigraphy of the Lower Carboniferous Horton Group, Nova Scotia; Contributions to Canadian Paleontology, Geological Survey of Canada, Bulletin 396, pp. 117-143.

Wightman, W.G., Scott, D.B., Medioli, F.S. and Gibling, M.R.m 1994. Agglutinatde foraminifera and thecamoebians from the Late Carboniferous Sydney coalfield, Nova Scotia: paleoecology, paleoenvironments and paleogeographical implications; Palaeogeography, Palaeoclimatology, Palaeoecology, vol. 106, pp. 187-202.

Worth, John Kirk, 1969. Stratigraphy of the Lower Horton Bluff Formation, Wolfville, Kings County, Nova Scotia; Acadia University, Wolfville, Nova Scotia; Unpublished M.Sc. thesis (Supervisor: R. Moore), 107 p.