Amber is widespread in association with coal and carbonaceous shale in probable equivalents of the Chandler and Prince Creek formations that crop out in the Kaolak River, Ketik River, and Kuk River valleys of the Alaskan Arctic Coastal Plain. Reworked amber is ubiquitous in recent stream deposits and in the Pleistocene Gubik formation. Fossil insect inclusions are rare, but as least four species representing the families Heleidae, Empididae, Eulophidae, and Ceraphronidae are present. The amber is generally associated with taxodiaceous fossils and is thus considered of taxodiaceous origin.
Marine fossils appear to be absent from the amber-bearing sequence. Thus biostratigraphic and time-rock correlation rests entirely on abundant plant megafossils and microfossils. Two floras occur with the amber. The older Kuk River flora is composed predominantly of gymnosperm remains and is considered Early Cretaceous. The younger Kaolak River flora, however, consists predominantly of angiospermous megafossils and gymnospermous microfossils. Thus it may be either Early or Late Cretaceous.