Sea-level changes through the Quaternary era have provided recurrent opportunities for the biosphere to significantly shape the coastal geomorphology of eastern Africa. Key agents in this shaping have been the calcium carbonate-fixing biota that have constructed the oceanfacing fringing reefs and produced the extensive backreef sediments that form the limestone platforms, cliffs and terraces th...

Soils can be disturbed by the burial of mines. When disturbed, the soils have a smaller effective size distribution than when undisturbed and this difference can be detected optically. Apparent emissivity differences in the thermal infrared is an effective passive optical technique developed by others for discriminating disturbed silicate soils from undisturbed soils and appears particularly se...

Northwest Borneo orogene. The shelf widens to more than 300 km toward the south in Sarawak and measures about 100 km in the north in Sabah. Structural deformation is most severe onshore and decreases toward the offshore, where all the currently producing East Malaysian fields are located. The two largest offshore oil fields, the Baronia field in northern Sarawak and the Samarang field in southe...

Stromatolites, laminated columnar and branched structures of limestone and dolomite, are the only macroscopic evidence of life for the first few billion years of earth history. These organo-sedimentary structures are a prominent constituent of Precambrian carbonate successions and occur sporadically throughout the Phanerozoic. They are hosts for metallic ores and serve as reservoir rocks for hy...

Quarrying in Scioto Township, Delaware County, Ohio, in 1966-67 uncovered an area of well-developed ripple marks at the top of the Columbus Limestone (Middle Devonian) and beneath a few inches of "bone bed" at the base of the overlying Delaware Limestone. The ripples averaged about 19 inches in wavelength and 1.5 inches in ripple height; they had smoothly rounded crests and were notably symmetr...

Major processes of the nitrogen cycle (i.e., nitrogen fixation, denitrification, ammonia mineralization and nitrification) were investigated in coastal sediments of several Seychelles Islands. Sediments were represented by carbonate sands, except in Victoria Harbor where they were carbonate silt. Nitrogen fixation was measured by acetylene reduction assay, other processes were studied by an exp...

Several countries, including Canada, contain sizeable bitumen resources in highly fractured carbonate rocks. Any possible recovery of bitumen from these reservoirs will be highly dependent on proper understanding of the rock and fluid properties and how they vary in the reservoir. These carbonates are extremely heterogeneous, and as a result proper reservoir characterization is challenging. In ...

Photosynthetic microbes, particularly cyanobacteria, that bore into carbonates are ancient biological players in various geologic phenomena such as the destruction of biogenic carbonates and coastal limestones, the reworking of carbonate sands and the cementation of microbialites. Their signatures are important tools for paleoenvironmental reconstruction, and they play a significant role in mar...

The concept of self-healing, whereby materials such as polymers, composites and cementitious construction materials are able to sense damage or deterioration and regulate, adapt and repair themselves automatically, is applied here to natural and anthropogenic soil structures. Damage in such structures can be difficult to detect and monitor, and will have significant consequences, but maintenanc...

Abstract Protocols for microbially induced carbonate precipitation (MICP) have been extensively studied in the literature to optimise process with regard amount of injected chemicals, ratio urea calcium chloride, method injection and intervals, population bacteria, usually using fine- medium-grained poorly graded sands. This study assesses effect varying urease activities, which not systematica...