Brand and Tang (1991) proposed that certain unusual vertebrate trackways "point to subaqueous deposition for at least part of the Coconino Sandstone." They supported their conclusions by demonstrating that western newts produce similar trackway configurations in aquarium experiments. While it is encouraging to see vertebrate ichnology play such a prominent role in fundamental questions concerni...

Introduction: Here we examine nucleation of self-organized spherical precipitates in porous and permeable media. Spheroidal concretions are common in geological environments and can arise through various geological or biological mechanisms, such as growth around an already existing nucleus (e.g. organic matter). Iron oxide concretions, however, often lack any obvious nucleus [1] and their prese...

The Pierre Shale is a marine deposit that accumulated in the Cretaceous Western Interior Seaway during the onset of Laramide tectonism in the southern Rocky Mountains region. In the eastern part of the Raton Basin near Trinidad, Colorado, ammonite biostratigraphy suggests that the base of the Pierre Shale lies within or slightly above the Lower Campanian Scaphites hippocrepis III ammonite range...

Sea urchins are dominant members of rocky temperate reefs around the world. They often occur in cavities within the rock, and fit so tightly, it is natural to assume they sculpted these "pits." However, there are no experimental data demonstrating they bore pits. If they do, what are the rates and consequences of bioerosion to nearshore systems? We sampled purple sea urchins, Strongylocentrotus...

The mechanical properties of any substance are essential facts to understand its behaviour and make the maximum use of the particular substance. Rocks are indeed an important substance, as they are of significant use in the energy industry, specifically for fossil fuels and geothermal energy. Attenuation of seismic waves is a non-destructive technique to investigate mechanical properties of res...

Deep-water massive (featureless) sands are commonly interpreted as indicators of flow conditions during or shortly after deposition and are almost never interpreted to reflect post-depositional homogenization due to bioturbation. Deep-water deposits of the lower Rio Dell Formation (Pliocene), Eel River basin (NW California), however, reveal previously unrecognized cryptically bioturbated fabric...

5 Interspecific relationships 48 INTRODUCTION 5 Predation 49 Location and geologic setting 5 Competition 50 Previous work 7 Commensalism 50 Approaches and study objectives 7 DEPOSITIONAL ENVIRONMENT AND Vertebrate paleontology 8 PALEOECOLOGIC SYNTHESIS 50 Paleobotany 8 Climate and paleogeography 50 Stratigraphy and correlation 8 Succession of the ancient communities 51 Acknowledgments 12 Summar...

Sand production is a universally encountered issue during the exploration of unconsolidated sandstone reservoirs particularly during production. The production of sand particles with the reservoir fluids depends on the stress around a wellbore and the properties of the reservoir rocks and fluids. Therefore, it is crucial to predict under what production conditions sanding will occur and when sa...

middle-late eocene deep marine deposits (483 m.) of the islam-ghaleh section, south mashhad, rich in ichnofossils in shale and sandstone layers. these flysch type sediments are composed of sandstone, shale and marl in gray to green in color and are divided into five subunits. the lower boundary of these successions is gradual with red conglomerate and sandstone and their upper boundary is gradu...