Original structures, especially stratification and cross-stratification, have been examined, analyzed and recorded for selected samples of modern beaches, dunes, alluvial fans, lagoons, and tidal flats in parts of western United States and Mexico. Some of these structures seem to be diagnostic of the environment represented. For example, cross-stratification of beaches can be recognized by the low angles and long, even surfaces of the foreshore laminae, especially where these are overlain by irregular erosion surfaces, channel profiles, and uneven bedding of backshore sediments as in deposits of a regressing sea. Dune deposits, in contrast, are composed almost exclusively of steeply dipping cross-strata that form on the lee slopes; the gently dipping cross-strata of windw rd sides, that slope in the opposite direction, rarely are preserved. Differences in basic types of dunes include minor variations in cross-stratification patterns.

Alluvial fan deposits exhibit a range in structures based on the types of deposits represented, that is, stream, stream flood, or sheet flood. Consequently, parts of a deposit may be sorted and stratified with preferred orientation of particles, whereas other parts are not. Fan deposits characteristically have low angles of dip--normally less than 10° and mostly less than 6°, as compared with the 10°-30° dips of talus slopes that form in similar situations.

Lagoon deposits have dominantly horizontal beds, but their structures are largely non-distinctive. Correct interpretation of this environment in ancient rocks depends on the recognition of distinctive structures in deposits of adjacent environments, especially the barriers that separate it from the sea, and on features of composition and texture.

Tidal-flat deposits, including black muds, fine sands, and shell accumulations, commonly include abundant ripple marks, channels filled with mud, flat-pebble conglomerates, tracks and trails, and drag marks. Stratification is in crude layers of variable thickness, essentially horizontal but non-persistent. Ripple laminae commonly are developed, but they may not be recognizable because of size sorting.