Extensive conglomeratic strata in the Late Jurassic to Early Cretaceous Tantalus Formation were deposited in both shallow gravel-bed braided rivers, and deeper meandering gravel bed rivers. Overbank, marsh and swamp deposits, with potential to contain abundant terrestrial organic materials, are restricted to recessive intervals associated with small sandy and gravelly highconstructive river systems. Medium- to high-volatile bituminous and anthracitic coals in these intervals have limited potential as a source of additional gaseous hydrocarbons. Most of the conglomerates have a high fracture density, which would make them good reservoirs for coal-bed methane in settings where the Tantalus Formation lies beneath a seal of younger volcanic strata. Strata of the Late Norian Mandanna member of the Aksala formation near Takhini Hotsprings do not contain fluvial strata: laminated, bioturbated, intraclast-bearing red sandstones were deposited in an intertidal setting, and may have lost most of their organic material prior to burial.
