We studied two short, high-gradient river systems draining the Dolomite Alps in northeastern Italy in order to determine which grain types survive transport and to what extent sand grain types reflect source rocks. Grains of all the labile rock types in the source areas survived to lower reaches of the rivers. In one drainage (Boite-Piave), they reached the Adriatic coast. Carbonate grains (largely dolomite) in the Gadera-Rienza Rivers decreased abruptly, largely by dilution, from >50% to trace amounts in 100 km of travel. Percentage of carbonate grains in the lower reaches of these rivers was generally less than one-half the areal percentage of limestone and dolostone exposure in the source areas. However, in the Boite-Piave Rivers (200 km long), enrichment of carbonate grains in beach sand at the expense of polycrystalline quartz and volcanic rock fragments results in dolostone sand at the beach reflecting 78% of its outcrop abundance and limestone (calcite) sand reflecting 68% of its outcrop abundance. Polycrystalline quartz and mafic volcanic rock fragments are less abundant in the beach because of dilution by longshore drift or the breakdown of these grains by wave abrasion. The relative resistance of carbonate textural grain types to abrasion is micrite > spar > mixed micrite/spar. The results indicate that detritus from dominantly silicic and intermediate volcanic rocks can survive fluvial transport and at least moderate wave abrasion. Metamorphic rock fragments (mostly phyllite) in the Gadera-Rienza Rivers survived transport to the confluence with the Isarco River at Bressanone. In the Boite-Piave river system, metamorphic rock fragments survived fluvial transport to the beach plus some beach abrasion. They did so because the relatively rapid transport down the high-gradient, low-sinuosity streams did not permit extensive chemical weathering. Grains of calcite (micrite and spar), dolomite, and volcanic rock fragments increased in roundness by abrasion in the surf after undergoing only a few kilometers of transport along the coast.

We studied the composition and roundness of medium sand from 18 small beaches of Elba Island. Six are pocket beaches less than 100 m long; the longest is 1.3 km long. The drainage basins of streams that supply the beaches are all less than 25 km 2 ; most are less than 5 km 2 . Beach sands range widely in composition owing to diverse source terrane. For the various drainage basins, comparison of the outcrop areas of the different types of bedrock with the compositions of beach sand grains yields the following conclusions: (1) the relative area of granodiorite outcrop is accurately represented by the amount of quartz + feldspar + quartzofeldspathic rock fragments in all beaches, although plagioclase in beach sand is significantly reduced relative to K-feldspar; (2) the relative areas of outcrop of ophiolitic and limestone bedrock are accurately represented by beach sand in pocket beaches, but are only moderately represented (ophiolitic rocks) or poorly represented (limestone) in other beaches; (3) the relative area of outcrop of metamorphic rocks is poorly represented in beach sand (metamorphic rock fragments + polycrystalline quartz) except in one anomalous beach supplied in part by mine tailings; (4) the relative area of bedded chert outcrop is poorly represented in beach sand because bedded chert does not break down into sand-size grains; and (5) shale bedrock is not represented or is only marginally represented in beach sand. For Elba beaches in general, the order of increasing roundness of grains, and thus increasing rate of abrasion, is: quartz < plagioclase < K-feldspar and igneous rock fragments (quartzo-feldspathic) < serpentine < metamorphic rock fragments < carbonate rock fragments (CRFs). There are no significant differences in roundness with beach length for quartz, K-feldspar, or CRFs. There are also no significant differences in roundness for the same three grain types from beaches of different size drainage basins, which indicates there is no perceptible rounding of grains by streams. First-cycle monocrystalline quartz grains of medium sand are unrounded, although coarser grains show minor blunting of edges. The roundness of quartz, K-feldspar, and CRFs are all greater on the eastern, more protected part of the island. This reflects a significant proportion of recycled quartz and K-feldspar in the eastern beaches, but CRFs may undergo more rounding in beaches of low to moderate wave activity than in high-energy beaches.

Abstract Most ancient eolianites possess a meager fossil record. Trace fossils and bioturbate textures are present, however, in eolian beds of the Entrada Sandstone (Jurassic) southeast of Moab, Utah. Three new ichnogenera and ichnospecies are described in this report. The most noticeable of the trace fossils are (rails ( Eniradichnus meniscus n. ichnogen. and ichnosp.) which parallel bedding planes in cross-stratified sandstone with we 11-developed parting lineation. Trails are long, unbranched, and gently curved. Many specimens contain an internal structure of meniscate backfill. The trails are oriented parallel to the depositional dip of cross-strata, suggesting that their creators moved down the lee sides of dunes, pushing sediment back up behind them. Similar meniscate trails are produced in modern sand dunes by the larvae of tipulid insects (“crane flies”). A second trace fossil type consists of small, vertical burrows ( Pustulichnus gregarious n. ichnogen. and ichnosp.) preserved as bumps in convex epirelief on cross-strata surfaces. These bumps may represent upward extensions of the meniscate trails described above, or they may represent shallow burrows made by sphecid Insects (“sand wasps”). Larger, plug-shaped, vertical burrows containing laminated fill ( Digitichnus laminatus n. ichnogen. and ichnosp.) are rare in the Entrada. Origin of these burrows is unknown. Moderate to thorough bioturbation of sandstone lenses also is present. Sedimentary structures that together indicate an eolian origin for the sandstone are: (1) large-scale, high angle (mean of 22°), sweeping cross-stratification; (2) large-scale soft sediment deformation, including small-scale soft sediment faulting; (3) eolian ripple marks (large ripple index and high ripple symmetry index) parallel to the dip of foreset slopes of cross-strata; and (4) multiple parallel-truncation bedding planes. Paleocurrent measurements are unimodal and suggest that winds blew to the south and southeast. Eolian petrographic characteristics of the sandstone are: (1) bimodal textures; (2) frosting of grains; (3) rounded or well-rounded coarser grains; (4) minor matrix; (5) high quartz content; (6) dominantly calcite cement; and (7) moderately to well-sorted grains. These ancient dunes are believed to have been formed in a sand sea where deposition persisted for a long period of time. Deposition was probably within 30° of the paleoequator, and the climate was semiarid or arid and hot.