The McCoy Brook Formation at Wasson Bluff

(back to map of basin)


Thick sections of the Early Jurassic age McCoy Brook Formation (the youngest syn-rift unit) outcrop along the north shore of the Minas basin. Locally, deposition of the strata was greatly influenced by left lateral strike-slip-related deformation during the earliest Jurassic (Olsen and Schlische, 1990). In the Wasson Bluff area, alluvial, fluvial, lacustrine, and eolian strata fill structurally controlled micro-basins on the faulted upper surface of the North Mountain basalt. Here is normal fault bounding part of tone of these microbasins. On the left is North Mountain basalt, and on the right is mostly eolian McCoy Brook Formation that was deposited against the scarp of basalt. Talus cones of basalt formed on interdune surfaces (as seen here) and blacks of talus fell directly onto the dunes slip faces.


The talus cones locally contain rich reptile assemblages, dominated by the crocodylomorph Protosuchus (Sues et al., 1996), otherwise known from the Glen Canyon Group of the western US and the Stormberg Group of southern Africa. Interdune surfaces produce surprising common prosauropod dinosaurs, both articulated and not. Uncommon fluvial sequences have produced the best preserved material such as this fine sphenodontid skull (photo courtesy of Hans Sues), a form also known from southern Africa (Sues et al., 1997) .


Lacustrine strata produce abundant dissarticulated fish remains as well as bits of dinosaurs and other reptiles.

These remains constitute the best well dated assemblage of tetrapods from the earliest Jurassic and show that the typical late Triassic forms did not survive into the Jurassic (Olsen et al., 1987).


Olsen, P. E. and Schlische, R. W., 1990, Transtensional arm of the early Mesozoic Fundy rift basin: penecontemporaneous faulting and sedimentation. Geology, v. 18, p. 695-698.

Olsen, P. E., Shubin, N. H. and Anders, P. E., 1987, New Early Jurassic tetrapod assemblages constrain Triassic-Jurassic tetrapod extinction event. Science, v. 237, p. 1025-1029.

Sues, H.-D., Shubin, N. H., Olsen, P. E., and Amaral, W. W., 1996, On the cranial structure of a new protosuchid (Archosauria: Crocodyliformes) from the McCoy Brook Formation (Lower Jurassic) of Nova Scotia, Canada. Journal of Vertebrate Paleontology, v. 16, no. 1, p. 34-41.

Sues, H.-D., Shubin, N. H., and Olsen, P. E., 1994, A new sphenodontian (Lepidosauria: Rhynchocephalia) from the McCoy Brook Formation (Lower Jurassic) of Nova Scotia, Canada. Journal of Vertebrate Paleontology, v. 14, no. 3, p. 327-340.