Paper No. 1
Presentation Time: 3:15 PM
LIGHT AIRCRAFT, TRENCHING TOOLS, AND INFLATABLES – OLD TOOLS USED FOR NEW FRONTIERS IN TRACE FOSSIL FIELD RESEARCH
New frontiers in ichnological research do not necessitate the use of new, expensive technology in order to extract significant information about trace fossils from outcrops. An abundance of information may await researchers in outcrops designated as non-ichnofossil-bearing units, covered, or inaccessible. Such tools as light aircraft, inflatable boats, and trenching tools can provide: 1) access to remote or difficult to reach outcrops; and 2) clean, workable exposures from which trace fossils can be documented, photographed, and collected. Light aircraft, although somewhat expensive to hire, can provide access to remote outcrops otherwise impossible to reach by other means. Inflatable boats and rafts are less expensive than light aircraft support and provide transportation to and from outcrops on rivers in accessible to very remote places. Trenching tools, particularly the folding blade and pick models used by the military and forest service, are excellent for trenching wide, deep swaths through weathered outcrops of interbedded mudrock, siltstone, and sandstone with a cover of mixed vegetation and talus. The remote setting of Arctic Alaska forces researchers to use complex logistics to reach outcrops, even in the summer months. Study of Cretaceous shoreface to coastal plain deposits exposed in bluffs along the Colville River on the North Slope requires light aircraft to land on remote gravelly point bars, inflatable rafts to cross the braided river to access outcrops, and trenching tools to expose weathered and or covered outcrop to obtain uninterrupted, quality data. Under-investigated, untrenched outcrop can provide misleading information regarding ancient depositional environments. For example, alternating sandstone-mudstone couplets in weathered outcrops appear similar to interbedded shale and tuff. Interpretation of paleoenvironments based primarily on reconnaissance studies, sedimentary logging of weathered outcrop, and laboratory analysis of grab samples may change radically when trenching exposes concealed trace-fossil distribution patterns. The value of trenching is unparalleled: fine-grained facies that might easily be mistaken for floodplain-dominated environments require re-interpretation as brackish-water or estuarine environments based on ichnofossils.