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cc:nerally finin. upw:l1d wt'CCS.Iion of silty/5afldy siliciclastic material. Imminent
emplKCmenl of the North~'eS1 Arm F.xmalion as I result of thrusting along the eastern
margin of the twin tener-ned Ioc:alised deposition of the Howe Harbour member. which
wu folkJwed by .. cessation of siliciclastic sedimerllation in those areas.
} J THE MAIN! AND FOB·..·ATION
The Mainland formation is restricted to llie west coast of the Pon au Port
Peninsula and contains a much higher proportion of sarK! than the American Tickle
formation. A number of different facies may be recognised.
U.l...fmn....b.ll 1· Thin IQ Medium.bedded SandsloDF
Facies MLI consists of thin- 10 thick-bedded fine- to medium-grained sandstone
(p~te 3.10) showina parlial or complete Bouma (1962) sequences. The most common
sequence is T"", with abundant ~lIellaminationsand putini lineations.
FluleS ue
common on basel of beds as are Crooves and other 1001 marks. Sevcrallhin beds show
spcclaC"ular load casts. The sandstone is friable and appears 10 have a high percentage
of mud. Black and green shale detritus is abundant on the planes ofparaJlellaminations.
The beds are latenilly continlJOU5 and do not vary in thickness. They are separated by
thin- to medium·bedded recessive sitty intervals.
The facies MLI lithology with its well developed Bouma (1962) sequences can
be classified as facies C2.:! (medium·bedded sand-mud couplets) and C2.3 (thin-hedGed
sand·mud couplets) using the classification scheme of Pickerinll et al. (1986). All were