Abstract

The “Northern Utah Highland,” although not an impressive topographic feature, is situated in a geologic setting which strongly suggests that it is the eroded remains of a very large crater which was greater than 40 miles (64.4 km) in diameter. The central part of the highland has a core of Precambrian rock. Peripheral to the core are ellipsoidal concentric belts of: (1) Cambrian, (2) Ordovician-Mississippian, and (3) Pennsylvanian-Permian strata. Radial faulting from the core area is also evident in some areas. Fold axes and thrust faults in the bedrock of the bordering mountains are either parallel to or slightly arcuate to the periphery of the highland.

The Northern Utah Highland has been previously dated by structural-stratigraphic evidence as having been formed at or near the Cretaceous-Tertiary boundary interval. The Cretaceous-Tertiary boundary event has been provisionally solved by the finding of a world-wide distribution of iridium in strata. Iridium is anomalously present in some meteorites, consequently investigators have been seeking an astrobleme at that interval. However, there are probably many rather than one which qualify, such as the Northern Utah Highland.

Certain data suggest that the short-term gradual, as well as catastrophic, extinctions of fauna and flora, as recorded in paleontological and stratigraphic studies, may be related to geomagnetic reversals. By using telescopic observations of the larger of the Moon’s craters and by comparing the Moon’s target cross-section with the Earth’s target cross-section, one can approximate the number of extraterrestrial asteroid or comet events which likely have impacted the Earth. A large impact event probably can cause a geomagnetic reversal. The geomagnetic data from the upper Late Cretaceous through the Tertiary records 182 magnetic reversals in a span of 84 million years. The time when clearly identifiable Proterozoic strata became established in a world-wide unconformity above the Archean crust occurred approximately 1,750 million years ago. Simple calculations involving the foregoing show that the larger impacts on Earth are in fair agreement with the number of calculated geomagnetic reversals which should have occurred from the time of initiation of the world-wide unconformity.