Published by the American Geological Institute
of the Earth Sciences
Neil A. Wells
|Stratigraphy, recently rejuvenated, is being
integrated into exciting large-scale models: e.g., G. Nichols'
and Stratigraphy (Blackwell, 1999), and Howell and van der Pluijm's
simplifying yet profound synthesis of Michigan basin stratigraphy
Society of America Bulletin, v. 111, p. 974, 1999).
In 1999, the International Association of Sedimentologists published two important Special Publications, v. 27 (Fluvial Sedimentology VI) and v. 28 (on paleoweathering). Both offer much to think about, such as Russell's description of the 1996 jokulhlaup in Iceland, Thiry's silcretes and Schwarz's polyphase saprolites. Tropical soil sedimentology, moribund too long, should be contributing to exciting recent upheavals in tropical terrestrial biosciences (e.g., Missouri Botanical Garden Annals, v. 86, p. 546, 1999).
Blair's studies of adjacent but very different alluvial fans in Death Valley (Sedimentology, v. 46, p. 913, p. 941, and p. 1015) showed that one was almost entirely mudflows and the other was almost all sheetfloods, because of bedrock differences. Surprisingly, both lacked expected proximal-distal facies trends.
Seas and lakes
Coastal studies benefited from a special issue (Geologie en Mijnbouw, v. 77, issue 3/4) on climate-related changes in European coasts, including a neat synthesis of eolian facies in Spain. The detail possible in interpretation is increasingly impressive. Pleistocene shoreline specialists are now carefully contrasting interglacials (lengthy interglacial stage 11 seems comparable to today and sea levels may have been about 13 meters higher (Science News, v. 157, p. 138, 2000). See also documentation of massive sedimentation on floodplains, shelves, and fans during highstands (Goodbred and Kuehl, Geology, v. 26, p. 559, 1999), and eustatically forced changes in coastal-plain interfleuve soils (McCarthy and others, Sedimentology, v. 46, p. 861, 1999).
Sulfur print showing the different layers in the
sediment of lake Cadagno in southern Switzerland.
Lehman and Bachofen ingeniously exploited sulfur chemistry to produce beautiful, detailed, self-developing, aphotic sulfur-print “photographs” (sulfographs?) of lake sediments and pore waters (Sedimentology, v. 46, p. 537).
Sedimentologists need to be aware of work going
on in other disciplines. Some physicists have been discovering crossbedding
and grain flows, without also discovering sedimentology (Nature,
v. 386, p. 379, 816, and 765, all 1997; v. 391, p. 136; v. 397, p. 675;
and v. 399, p. 211 and 241, all 1999). One author wonders in effect if
tongue-shaped sand flows might ever be found in nature; another discovers
angles of repose and uphill recession of grainflow heads, and a third hopes
that adding water to dry-sand experiments might lead to "new physical phenomena."
Wells teaches sedimentary
geology and geomorphology at Kent State University in Kent, Ohio. He researches
modern and ancient alluvial fans and rivers. E-mail: email@example.com
The author recommends Schlager's predictions for sedimentology's future (Journal of Sedimentary Research, v. 70, p. 2, 2000), with respect to employment in oil, water and environmental sectors, and research in geomicrobiology, predictive stratigraphy and climate change.