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101.
102.
James J. Bell 《Marine Ecology》2002,23(4):297-311
Abstract. The sponge communities inhabiting a temperate semi-submerged sea cave were investigated at Lough Hyne Marine Nature Reserve, Co. Cork, Ireland. Thirty-one species of sponge were reported, the majority of which exhibited either an encrusting or massive morphology. Sponge density (averaged over depth) increased with horizontal distance (5 m intervals) into the cave until approximately 30 m, corresponding to the maximum algal intrusion (algal information from Norton et al. , 1971) . Species diversity and richness (averaged over depth) were highest at 10 m horizontal distance from the cave entrance. Variability in sponge density, diversity and richness was observed with increasing vertical depth (0.5 m intervals) at most horizontal intervals sampled (5 m apart). These three variables increased initially with depth, but then decreased towards the seabed. Bray-Curtis Similarity Analysis and Multi-Dimensional Scaling (MDS) showed cave sponge community composition to have greater similarity (50 %) with local loose rock habitats than the nearby cliffs. Similar processes structuring cave and loose rock sponge communities may account for this situation. Information collected from this and previous studies on the biotic (algal communities, other fauna and competition) and abiotic factors (water flow rate, depth, aerial exposure, light, cave morphology, nutrient depletion and humidity) affecting this and other caves is discussed with respect to its influence on the sponges inhabiting different parts of the cave. Although horizontal zonation patterns have been considered analogous to vertical distribution patterns for algal communities (due to similar decreases in light), this was not the case for the studied sponge communities. 相似文献
103.
The cave bear was a prominent member of the Upper Pleistocene fauna in Eurasia. While breakthroughs were recently achieved with respect to its phylogeny using ancient DNA techniques, it is still challenging to date cave bear fossils beyond the radiocarbon age range. Without an accurate and precise chronological framework, however, key questions regarding the palaeoecology cannot be addressed, such as the extent to which large climate swings during the last glacial affected the habitat and possibly even conditioned the final extinction of this mammal. Key to constraining the age of cave bear fossils older than the lower limit of radiocarbon dating is to date interlayered speleothems using 230Th/U. Here we report new results from one such site in the Eastern European Alps (Schwabenreith Cave), which yielded the highest density of bones of cave bear (Ursus spelaeus eremus). Although dating of the flowstones overlying this fossiliferous succession was partly compromised by diagenetic alteration, the 230Th/U dates indicate that the bear hibernated in this cave after about 113 ka and before about 109 ka. This time interval coincides with the equivalent of Greenland Stadial 25, suggesting possible climate control on the cave bear's habitat and behaviour. © 2019 The Authors. Journal of Quaternary Science Published by John Wiley & Sons Ltd 相似文献
104.
The Chan Hol cave near Tulum (Quintana Roo,Mexico): evidence for long‐lasting human presence during the early to middle Holocene
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<正>Mushroom Mountain karren with predominantly flat tops that formed along the stylolites and bedding planes dictated the special features of this karst landscape.Their features and rock relief clearly reflect the geological conditions and development.The subsoil karren with conical tops dissected by subsoil rock relief were exposed from beneath the soil.Below tree vegetation,the subsoil karren are to a great extent covered by moss and lichen,under which they acquire their characteristic shape.On the bare surface they were reshaped by rainwater that carves flutes and solution pans.The old cave that opens below the top of one of the cones reveals the period before its dissection into hills and cones when this part of the karst aquifer was still deep under the water table. 相似文献
107.
雷旭友 《物探化探计算技术》1998,20(2):175-178
南宁~昆明铁路共进行了238km路基、隧道、车站、桥址的岩溶综合物探,依据物探结果,进行了3500多个钻孔的岩溶整治,钻孔资料为物探资料的再分析、总结、提高提供了极为丰富翔实的已知资料。本文通过了三个典型的厅状大溶洞电探信息分析,初步总结出该类异常的反映特征和规律。 相似文献
108.
应用浅层地震技术勘查岩溶及溶洞 总被引:2,自引:0,他引:2
本文结合工程勘查实例,介绍了浅层地震技术(高密度地震映象法和横波法)在解释工程勘查中探岩溶,溶洞问题的应用,分析岩溶,溶洞等在浅层地震勘探中表现的特征和规律,并探讨其应用效果。 相似文献
109.
云南石林洞穴发育特征初析 总被引:5,自引:0,他引:5
石林位于滇东喀斯特高原南部,喀斯特极其发育,以发育了典型的石林地形面闻名退途,倍受国内外喀斯特学者的关注。研究区内喀斯特洞穴极为发育,洞穴在发育分布上受到区域碳酸盐岩地层分布的控制,表现出洞穴分布的相对集中性、洞穴发育对地层的选择性和洞穴发育的成层性等特征。洞穴发育规模绝大多数为中小型洞穴;洞穴多为现代地下洞河,埋藏浅且多天窗,并且洞穴的发育延伸方向明显受裂隙构造的控制,有强烈的方向性。通过对石林地区喀斯特洞穴的发育延伸方向明显受裂隙构造的控制,有强烈的方向性。通过对石林地区喀林斯特洞穴发育条件、洞穴发育规模、分布特征和洞穴发育的古地理环境特征的条件,论述了石林地区洞穴的发育特征。 相似文献
110.
在城市建设中,为保证工程质量及施工进度,应用物探方法探查地基坚固性,是一卓有成效的方法。本文论述了应用多源排列电阻率测深法及坑道-地面电阻率法在北京中国新闻学院及八王坟地铁站所取得的良好成果。该成果已经验证,并为生产部门采用。 相似文献