The Flume Formation exposed in Jasper National Park is a widespread sheet-like carbonate body, 100 to 250 ft thick, which served as a platform for the overlying 1200-ft thick, areally restricted Miette bank of the Cairn and Southesk formations.
Platform deposition began on a pre-Devonian erosional surface that had a topographic high beneath the present Miette bank. During marine transgression across this surface, a broad shelf lagoon formed in which shallow subtidal to supratidfal carbonates of the platform evolved. Shoaling conditions were maintained throughout platform evolution over this paleohigh by carbonate sedimentation buildup and perhaps gradual uplift. During relatively rapid inundation, most of the platform was covered with basinal carbonate mudstones of the Perdrix Formation; on only the shoalest parts of the platform were stromatoporoids able to survive. In essence, the overlying Miette bank represents localized continuation of platform growth.
The following lateral facies changes occur in the platform in a bankward direction: 1) the lower platform member thins; 2) the upper platform member thickens; 3) in the upper platform member, tidal-flat and shallow subtidal deposits appear and thicken, and deeper subtidal deposits thin and disappear. These changes occur most rapidly within 1 to 5 mi from the bank.
Widespread carbonate units that served as platforms for overlying banks can be important both in determining bank proximity and in understanding relationships between platform genesis and bank inception and localization.