Using pebble lithology and roundness to interpret gravel provenance in piedmont fluvial systems of the Rocky Mountains, USA

New physical evidence of the role of stream capture in active retreat of the Blue Ridge escarpment, southern Appalachians

“…Clast roundness is known to increase with progressive fluvial transport such that the shape of clasts in alluvium preserved at the divide may be inverted to obtain the magnitude of channel length lost to BRE and divide retreat (Mills, 1979;Lindsey et al, 2007). Sadler and Reeder (1983) offered an empirical and field-expedient method for relating the roundness of quartzite clasts to transport distance.…”

Paleocurrent and fabric analyses of the imbricated fluvial gravel deposits in Huangshui Valley, the northeastern Tibetan Plateau, China

“…In theory, roundness increases with the distance a clast has traveled in a given stream, and thus can be used as evidence for the distance a clast has been transported, and in some cases for the flow direction (e.g., Lindsey et al, 2007). But, as field and laboratory studies have indicated the increase is most rapid in the first few kilometers of transport, and reaches a dynamic equilibrium quickly, making it a parameter with only limited potential for determining travel distance (Potter and Pettijohn, 1977).…”

Abiotic and Biotic Links Work Two Ways: Effects on the Deposit at the Cliff Foot Induced by Mechanical Action of Date Mussel Harvesting (Lithophaga lithophaga)

“…This allows to conclude that unexpected differences in the roundness of pebbles in shallow water deposits not only reflect a different history of abrasion, transportation or solution (e.g. Lindsey et al 2007), but may also indicate a different history of impact to DMH activities. From this perspective, in presence of areas impacted by DMH, that in some cases affects entire coastline sectors wide hundreds of km (Fanelli et al 1994 report of a DMH impact along the Apulian coastline in 105 km above 159 km of inspected rocky coast), paleo-beach pebble deposits can be obliterated, loosing one of their peculiar characteristics (high roundness of clasts) and therefore leading to misunderstandings in their interpretation.…”

“…Beach (and paleo-beach) pebbles are characterized by a high R index, and unexpected differences in the roundness of pebbles in a deposit may usually reflect a different history of abrasion, transportation, or solution (e.g. Lindsey et al 2007).…”