Abstract Eolian deposits tend to be well sorted sands and silts which frequently form a distinctive component of proglacial depositional sequences. However, they vary in importance in continental glacigenic sequences, from more than a hundred meters thick (loess deposits) to no deposits at all. The availability of easily eroded sediment coupled with sparse vegetation and strong persistent winds in the region of an active glacier enhance eolian activity. Erosion, transportation and deposition by wind occurs before, during and following glaciation, however, the thickness of the deposits is spatially varied. The thickest deposits accumulate in and along river valleys often beyond the terminal position of ice. In general, deposition occurs in a zone fringing the glacier terminus. The zone shifts laterally following the ice during recession producing a time-transgressive deposit. Subsequent encroachment of vegetation tends to stablilize the deposits and reduce or terminate eolian activity. Thus, abundant available sediment, sparse vegetative cover, and katabatic winds off the glacier provide optimal conditions for eolian transport and deposition. Eolian sands (medium to fine sand) commonly associated with outwash and glacial lake deposits become thinner and finer grained with distance from the source and grade into eolian silt (loess). In general, eolian deposits tend to mantle topography irrespective of elevation, and unlike water-laid sediments are not controlled by base level. Thus, windblown sediments may be adjacent to, interbedded with, or cover other glacigenic deposits. Their distribution is either as: (1) a thin 1-2 m blanket called a ucoversand in Europe (Cailleux 1942) and an “eolian

Abstract The Holocene eolian barrier of the Younghusband peninsula, South Australia, is an accessible and well-studied modern analog for ancient eolian carbonate and mixed quartz-carbonate barriers, as well as the associated suites of sedimentary structures that might be expected in such settings. The barrier has formed from the shoreward drift of Lacepede Shelf biogenic carbonate fragments as well as the longshore drift of quartz sand from the Murray River. The Younghusband barrier carbonate content increases from roughly 12 percent at the mouth of the Murray River southeastward to nearly 75 percent at Lacepede Bay, near Kingston. The barrier consists mainly of eolian dune and sand-sheet deposits. Dune bedforms consist of parabolic, blowout, coppice, and various subtypes of transverse dunes including barchan, barchanoid ridge, and transverse ridge dunes. There is a low foredune along the shore, landward of which lies a narrow sabkha mat separates this foredune from the main barrier. Where vegetation has been destroyed or thinned, deflation forms large blowouts, parabolic dunes, and transverse dunes, whose advance is causing the barrier to shift northeastward into the Coorong Lagoon. The abundant carbonate material within the barrier includes transported bryozoans and coralline algae that originated on the cool-water Lacepede Shelf. These materials, along with broken shells of lagoonal and nearshore fauna such as gastropods and mollusks, have been incorporated into the cross stratification. This process has produced such coarse, shelly textures in the eolian barrier sediments, particularly the sand-sheet deposits, that it would be difficult to identify these sediments as eolian in the ancient record. This is not merely because of the presence of shell debris but also because of unusual sedimentary structures. Nevertheless, common eolian sedimentary features are present and identifiable, and provide a key to proper interpretation of this group of sediments in ancient rocks. The Holocene Younghusband barrier and the landward Pleistocene carbonate barriers are viable analogues for subsurface petroleum reservoirs. The Younghusband barrier, if buried and preserved, would be a very narrow but elongate sand lens about a kilometer wide at maximum, and up to 30 meters thick, with enormous reservoir volume because of its great length. It would consist mainly of clean eolian sands, composed dominantly of either quartz or carbonate depending upon position along the barrier. These sediments would be interbedded with nearshore and lagoonal facies (potential source rocks). Recognition of the eolian nature of such a barrier-originated petroleum reservoir would allow correct paleogeographic placement of the sediments, and would facilitate both development drilling and further exploration for new barriers or extensions of the current field. Further, the knowledge that the modern barriers exist in trends controlled by sea-level stands would suggest that petroleum reservoirs in such ancient systems might occur in multiple fields parallel to bathymetric contours of an ancient marine shelf. The current preservation of eolian parts of older barriers in the South Australia region onshore but below sea level (observed in shallow-drilling programs) and offshore as subsea “ranges” proves that such preservation of the eolian component of barriers is not only possible but should be expected in the ancient record.