Photographs of Physical Structures

This photograph shows detail of ripples on Joulter's Cay ooid shoal. Note the rounded crestlines and variable plan morphology of the ripples. Ripples are superimposed on low dunes oriented roughly perpendicular to ripple crest orientation. Ripple spacing approximately 100mm.

Large-scale cross-stratification in Upper Paleozoic grainstones. Skeletal-peloidal grainstone unit in the Mississippian Loyalhanna Limestone from central Appalachians. Cliff face is 19.5m high. Lower 3m and upper 6m mostly flow-parallel views. Central 10m shows flow-perpendicular and oblique views of large troughs.

Reactivation surface in cross-stratified Paleozoic grainstones. Composite set of large-scale cross-strata developed in quartz sand-bearing, skeletal-peloidal grainstones, Mississippian Loyalhanna Limestone, central Appalachians. The four flow-parallel sets of cross-strata that comprise the upper two-thirds of the outcrop include many reactivation surfaces, some of which have small-scale ripples directed up the foreset slope(arrows).

Flow paralle view of wave-ripple form set(upper arrow) overlying flow oblique view of wave-ripple cross-stratification(lower arrow). Dolomite mud drapes both cross-stratal sets. Middle Cambrian Arctomys Formation, Canadian Rocky Mountains, southwestern Alberta.

Wavy to crinkled fine laminae composed of couplets of grainstone layers(dark) and dolomitic mudstone layers(light). Upper Cambrian Conococheague Limestone of the central Appalachians.

Planar laminae(greater than 5mm thick) and thin beds developed in dolomite mudstone, Lower Proterozoic Wittenoom Dolomite, Hamersley Basin, Western Australia. Pocket knife, lower left center, is approxiately 80mm long.

Flat pebble conglomerate from the Upper Silurian Wills Creek Shale of the Central Appalachians. Clasts overlie sharp erosional truncation of underlying fine, wavy-laminated, fine-grained peloidal grainstone and are themselves composed of cross-stratified and planar stratified fine-peloidal grainstone. Clasts in upper third of bed are imbricated, flow from left to right. Note the shelter porosity developed beneath many of the clasts suggesting they were not deposited on the foresets of dunes.

Cross-sections of mudcrack fills from the Middle Ordovician St. Paul Group of the central Appalachians. Note that the cracks contain several generations of sediment fills with a micro-stratigraphy relatable to overlying layers. These observations demonstrate that these cracks were open at a sediment-air or sediment-water surface a number of times and that these cracks could not have formed from upward "injection" of sediment.

Convolute folding in crinkled laminated mudstones from the Upper Silurian Tonoloway Formation, western Maryland.

Small stromatolitic bioherm encased in thin beds of carbonate mudstone that bend around the bioherm from both above and below. Affected beds thin laterally above and below the bioherm and show increasing dips and thicknesses down the sides of the bioherm. Beds asre thickest along the flanks of the bioherm and thin laterally as well. Upper Cambrian Conococheague Limestone, western Maryland.