THE OGDEN CANYON CONGLOMERATE

Ogden Canyon is located in the Wasatch Mountains east of Ogden, Utah, along the margin of the Basin and Range Province of the western United States. Within this canyon are the remnants of a 60 m thick deposit of poorly sorted conglomerate which had infilled the canyon to an elevation of 1435 m. The clasts making up the conglomerate range in size from large boulders to gravel within a sandy matrix cemented by calcium carbonate. The clasts include quartzite derived from the Cambrian Tintic Quartzite and limestones from the Mississippian Humbug, Gardison and Deseret formations. There are also metamorphic clasts present near the mouth of the canyon which were derived from the precambrian Farmington Canyon Metamorphic Complex. The clasts are generally sub-angular to well-rounded, and spheroidal in shape. There is evidence of bedding, and in general individual beds fine upwards as does the entire sequence. Muddy poorly lithified silts cap the sequence. The conglomerate was deposited subaqueously, most likely during the transgression of Lake Bonneville to the Bonneville level prior to 15 ka. There is evidence of a brief period of subaerial exposure interrupting the transgressive cycle characterized by the preservation of channel forms that are bounded above and below by the conglomerate. There is little evidence of wave reworking of the sediments, indicating that during the transgression the rise of the lake level possibly outpaced sedimentation. The extent of the deposit was mapped using ArcInfo 8.3 from field data gathered using GPS. A reference section for the Ogden Canyon conglomerate is designated and a measured section is presented.