The Battery Point Formation (Emsian) forms part of a broadly upward-coarsening alluvial suite. The formation is 2,300 m (7,550 ft) thick, rests unconformably on shallow marine sandstones of the York River Formation, and is transitional upwards into a proximal braid-plain sequence of the Malbaie Formation.

A lower, 110 m (360 ft) thick, sequence from the Battery Point was previously interpreted as braided-fluvial based mainly on the recognition of laterally migrating, shallow transverse bar deposits and on a paucity of vertically accreted fine-grained sediment.

Between Cap-aux-Os and Penouille, Gaspe Peninsula, these braided-fluvial facies are succeeded by quite different fluvial deposits mainly comprising 30-40 m (100-130 ft) multistory channel sandstone complexes, often thinning laterally to 15-18 m (50-60 ft), and separated by 6-10 m (20-33 ft) of laterally persistent mudrock sequences. The latter can be traced laterally up to 6.5 km (4 mi), allowing the geometry of the sandstones to be evaluated in great detail.

Within the sandstones, medium-scale trough cross-bedding is dominant, with subordinate, isolated (0.8-3 m or 32 in.-10 ft thick) planar-tabular sets and parallel laminated units. Mudclast-lined erosion surfaces commonly define individual channel-fill events.

The scarcity of cut-bank phenomena, and lack of lateral accretion surfaces suggest laterally unstable channels of fairly low sinuosity within large (possibly up to 15 km or 9 mi wide) stable channel belts. These were rapidly abandoned, accumulating the mud-rock sequences, which are exceptionally up to 50 m (165 ft) thick. The paucity of desiccation features and lack of mature calcretes, together with abundant plant activity and much wave rippling, suggest that large areas of standing water existed on the flood plain.

Extrinsic controls, such as climatic change, are proposed for this evolution in fluvial style.

End_of_Article - Last_Page 499------------