Palaeolithic Art and Natural Rock Formations

1982 ◽  
Vol 23 (5) ◽  
pp. 567-569 ◽  
Eos ◽  
2011 ◽  
Vol 92 (38) ◽  
pp. 324-324
Author(s):  
Colin Schultz

1996 ◽  
Vol 15 (1) ◽  
pp. 3-24 ◽  
Author(s):  
Scott Montgomery

The first naturalistic drawings of geologic phenomena, particularly rock formations, are assumed by historians to have occurred early in the 19th century, when geology matured as a science. No less than three centuries earlier, however, the Netherlandish master, Jan Van Eyck, drew exposures of natural rock whose features are so remarkably accurate as to permit modern-day geologic analysis of their lithology, fossil content, sedimentary structures, and depositional environment. Van Eyck clearly studied, drew, and painted a specific outcrop "in the field," long before such practice had become common in art or science. As the first modern geologic "observer," Van Eyck greatly extended an existing tradition of naturalism with regard to organic phenomena (esp. plants, insects, human figures) fully into the realm of inorganic reality. In this, he far surpassed other scholar-artists, such as Leonardo da Vinci, who have been credited with similar achievements. Van Eyck's achievement proved exceptional. It was matched neither by later artists, scientists, or illustrators until the late 18th-early 19th century, when conventions in travel literature and landscape inspired new attention to the drawing of rock materials. The reasons for this historical gap have everything to do with the limitations of observation in early geological study, which show important parallels to those in art.


Author(s):  
John M. Wehrung ◽  
Richard J. Harniman

Water tables in aquifer regions of the southwest United States are dropping off at a rate which is greater than can be replaced by natural means. It is estimated that by 1985 wells will run dry in this region unless adequate artificial recharging can be accomplished. Recharging with surface water is limited by the plugging of permeable rock formations underground by clay particles and organic debris.A controlled study was initiated in which sand grains were used as the rock formation and water with known clay concentrations as the recharge media. The plugging mechanism was investigated by direct observation in the SEM of frozen hydrated sand samples from selected depths.


Minerals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 779
Author(s):  
Mohamed Gomah ◽  
Guichen Li ◽  
Salah Bader ◽  
Mohamed Elkarmoty ◽  
Mohamed Ismael

The awareness of the impact of high temperatures on rock properties is essential to the design of deep geotechnical applications. The purpose of this research is to assess the influence of heating and cooling treatments on the physical and mechanical properties of Egyptian granodiorite as a degrading factor. The samples were heated to various temperatures (200, 400, 600, and 800 °C) and then cooled at different rates, either slowly cooled in the oven and air or quickly cooled in water. The porosity, water absorption, P-wave velocity, tensile strength, failure mode, and associated microstructural alterations due to thermal effect have been studied. The study revealed that the granodiorite has a slight drop in tensile strength, up to 400 °C, for slow cooling routes and that most of the physical attributes are comparable to natural rock. Despite this, granodiorite thermal deterioration is substantially higher for quick cooling than for slow cooling. Between 400:600 °C is ‘the transitional stage’, where the physical and mechanical characteristics degraded exponentially for all cooling pathways. Independent of the cooling method, the granodiorite showed a ductile failure mode associated with reduced peak tensile strengths. Additionally, the microstructure altered from predominantly intergranular cracking to more trans-granular cracking at 600 °C. The integrity of the granodiorite structure was compromised at 800 °C, the physical parameters deteriorated, and the rock tensile strength was negligible. In this research, the temperatures of 400, 600, and 800 °C were remarked to be typical of three divergent phases of granodiorite mechanical and physical properties evolution. Furthermore, 400 °C could be considered as the threshold limit for Egyptian granodiorite physical and mechanical properties for typical thermal underground applications.


Membranes ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 587
Author(s):  
Run Shi ◽  
Huaiguang Xiao ◽  
Chengmeng Shao ◽  
Mingzheng Huang ◽  
Lei He

Studying the influence of grain characteristics on fluid flow in complex porous rock is one of the most important premises to reveal the permeability mechanism. Previous studies have mainly investigated the fluid flow laws in complex rock structures using an uncontrollable one single parameter of natural rock models or oversimplified control group models. In order to solve these problems, this paper proposes a novel method to reconstruct models that can independently control one single parameter of rock grain membranes based on mapping and reverse-mapping ideas. The lattice Boltzmann method is used to analyze the influence of grain parameters (grain radius, space, roundness, orientation, and model resolution) on the permeability characteristics (porosity, connectivity, permeability, flow path, and flow velocity). Results show that the grain radius and space have highly positive and negative correlations with permeability properties. The effect of grain roundness and resolution on permeability properties shows a strong regularity, while grain orientation on permeability properties shows strong randomness. This study is of great significance to reveal the fluid flow laws of natural rock structures.


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