Catálogo de publicaciones - revistas

<jats:title>Abstract</jats:title> <jats:p>The best-exposed natural bedrock outcrops in Michigan's southern peninsula are Upper Carboniferous (Pennsylvanian) sandstone ledges underlain by silts, clays, and coals in classic midcontinent ‘cyclothem’ stratigraphy, exposed along the Grand River in the city of Grand Ledge. Native Americans used the underclay in pottery; later commercial mining was the basis for clay-products factories. In the 1800s, the ledges provided a picturesque setting for a resort economy. Among the beneficiaries of repurposed quarries (now parks) are generations of Michigan geoscience students. A trip to Grand Ledge is often the first geology field experience for many students and plays an important role in the professional development of practising geoscientists and geoscience educators in Michigan. After an announcement of plans to expand the city's water treatment plant, adjacent to the cyclothem exposure, geologists from academia, government, and industry united to support preservation of the outcrops. City officials, previously unaware of the geoheritage value of the rocks exposed in their parks, are willing to work with geoscientists to preserve the site. This experience underscored the importance of documenting the geoheritage of the Grand Ledge area and establishing relationships with those who have oversight of these ‘greatest outcrops’ to ensure their preservation for future generations.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Large boulders, up to several metres in diameter and mainly made up of metamorphic rocks, are scattered throughout the Torino Hill in NW Italy. These boulders were originally included in Oligocene–Miocene conglomerate beds and were released by alteration of the host rock at the surface. In the past two centuries, their origin and mechanisms of emplacement in the conglomerate bodies were largely debated by both Italian and foreign geologists. Some of the boulders had been given proper names by the local people and had become the object of legends and rituals. Moreover, in the past, the boulders had an economic value, being used as construction stones or exploited to produce aggregates, lime and millstones. This, together with the progressive urbanization of the area, caused the disappearance of many of the large boulders once present on the Torino Hill. The remaining ones are presently not appreciated and are almost forgotten, even though they represent an invaluable geoheritage and deserve rediscovery and protection.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The Sea Point intrusive contact on the Atlantic coast, South Africa, is a site of historical significance which continues to be useful for studying the details of granite-wallrock relations, some of which have not been properly evaluated yet.</jats:p> <jats:p>At a time when the origin of granites was still controversial, and the concept of contact metamorphism not yet properly developed, Charles Darwin visited the Sea Point contact to make some geologically important observations. He concluded that the granite originated as a magma deep in the earth, intruded a country rock of sedimentary origin and changed this country rocks' appearance due to the thermal action of the hot granite magma. He also contemplated the long periods of time required to expose the rocks by erosion. Besides its historic value, the Sea Point heritage site exposes unique features giving rare insights into the physical and chemical interaction between intruding granitic magma and a regionally low-grade metamorphosed sedimentary sequence.</jats:p> <jats:p>Questions regarding mechanisms of magmatic emplacement may be answered from this outcrop, including emplacement dynamics and interrelationships of various granitic phases, pre- versus syn-intrusive deformation and metamorphism, assimilation of country rock by a granitic magma, and the origin of feldspar phenocrysts seemingly “stranded” in the country rock.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The Great Valley of Virginia (GVV) is a section of a much larger geological structure that spans from the northeastern USA through the mid-Atlantic and to the SE. While the structural formation of the region represents nearly 1.2 billion years of geological history, the rocks that remain record vast cycles of tectonic change. The legacy of that geology is a rich and aesthetically attractive region that has drawn many peoples over time to its agricultural fertility and geological resources. This contribution traces the geological development of the GVV, the relationship of the GVV to the peoples, both indigenous and European colonizers, who have inhabited the GVV over thousands of years and the geological resources that the inhabitants found. Although relatively under-expressed from a geoheritage perspective, the GVV possesses a rich legacy of how its resources supported each society's needs and interests and the role its geological environment has played at critical moments in the historical development of the USA over the last 400 years.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The Falls of the Ohio is a world-renowned geoheritage site of palaeontological and geological importance that also played key roles in the cultural and historical development of America. Studied by geologists for over two centuries, over 600 species of fossils are known from the site, hundreds which were first described here. Beyond geology, the Falls of the Ohio can also be considered the origin and ending of the Lewis and Clark expedition, as well as an important location for naturalists and educators. A treasure of natural and human history and a National Natural Landmark, this spectacular 220-acre expanse of fossiliferous bedrock is worthy of ongoing study and protection.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Since the last Special Publication on seismic geomorphology, the application of seismic data has grown substantially, revolutionizing our understanding of basin evolution in the process. The papers presented here provide an insight into the direction of travel for seismic geomorphological analyses and how the science has evolved since 2007. New methods of data collection, new methods of processing and visualization, and the integration of new types of complementary data, all have played a role in maximizing the potential palaeo-environmental insights that can be derived from such studies. The submissions range across different geological settings, consisting of glacial, fluvial, volcanic, deltaic and slope settings. Many of these studies integrate different methods, showing what can be achieved by combining multiple datasets to understand the subsurface. As more legacy datasets become available, the observed acceleration in seismic data availability and the associated publications will likely continue. Newer methods and greater knowledge of the subsurface are yielding a greater understanding of not just the palaeoenvironments, but also what generates seismic reflectivity in the subsurface. The study of seismic geomorphology remains in its infancy, and much exciting research potential is yet to be realized.</jats:p>

<jats:title>Abstract</jats:title> <jats:p> 3D seismic data provide new insights on <jats:italic>c.</jats:italic> 2 km thick Cenozoic post-transform slope sediments and fluid-flow phenomena along the Nigerian Transform Margin. The study documents large-scale mass-transport deposits (MTDs), deep-water channels, sediment waves, and a range of fluid-flow phenomena such as pockmarks, pipes, seabed mound and gas hydrates. They are observed from Pliocene-aged sediments and distributed above structural highs, regional faults, and active and relict deep-water channels in the eastern part of the area, closest to the Niger Delta cone. The fluid-flow features are interpreted to be indicative of an active petroleum system in the deeper subsurface and from fluid migration along planes of deep-seated faults. MTDs are mapped at multiple levels and the volume of failed sediments increased through time within the western part of the study area. The repeated and increased volume of MTDs in the area is attributed to an increased rate of sedimentation through time and slope gradient during the late Cenozoic. The presence of repeated MTDs and fluid-flow phenomena on the Nigerian Transform Margin has implications for installations of offshore facilities as they constitute potential geohazards. The study also documents, for the first time, polygonal fault systems offshore Nigeria. </jats:p>

<jats:title>Abstract</jats:title> <jats:p>Grand Caverns is known to be the oldest show cave in continuous operation in the contiguous United States (US). Discovered in 1804, Grand Caverns has been offering tours, at least one per year, continuously from 1806 until now. For more than two centuries Grand Caverns, host to diverse and uncommon solution caves' speleothems such as cave shields, has served as the center of multidisciplinary research related to the understanding limestones in Virginia and has accrued historical accounts relevant to the Shenandoah Valley (nestled between the Blue Ridge Mountains to the east and the Allegheny Mountains to the west) in the Commonwealth of Virginia. In this chapter, we explore the geological, historical, mapping, and geotourism legacies, while using the Geoheritage as a narrative framework. In addition, we discuss the intersection of historical and diverse concurrent heritages at Grand Caverns and the relevance for the understanding of national show caves and caves' development processes; and we share ongoing efforts towards the construction of a proposal to elevate the status of Grand Caverns to be part of the United Nations Educational, Scientific and Cultural Organization (UNESCO) World Heritage list.</jats:p> <jats:p content-type="supplementary-material"> Supplementary material at <jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="uri" specific-use="dataset is-supplemented-by" xlink:href="https://doi.org/10.6084/m9.figshare.c.7027515">https://doi.org/10.6084/m9.figshare.c.7027515</jats:ext-link> </jats:p>

<jats:title>Abstract</jats:title> <jats:p> The cliffs and foreshore at Lyme Regis on the Dorset coast expose a sequence of Early Jurassic marine limestones and mudstones of the Blue Lias Formation and the overlying Charmouth Mudstone Formation, the lowest units of the Hettangian-Aalenian Lias Group. Known for its fossils since at least the mid-seventeenth century, this coastal section became famous in the early nineteenth century for the bones of ‘fossil crocodiles’. Many of the most significant discoveries were made by a family of fossil dealers whose best-known member was Mary Anning (1799–1847). Anning and her family recovered the first scientifically described ichthyosaurs, the first complete plesiosaur, and the first British pterosaur to be identified. Anning's finds from Lyme Regis formed the basis of the pioneering palaeoenvironmental reconstruction <jats:italic>Duria antiquior</jats:italic> . Her geologist friends, some with close personal associations to the town, did much to publicise her discoveries and contribute to both her fame and that of the locality. This famous coastal section, with its important historical associations with a key period in the development of geology and the source of so many significant discoveries in the early nineteenth century, now lies within the Jurassic Coast UNESCO World Heritage Site. </jats:p>

<jats:title>Abstract</jats:title> <jats:p>The Walcott Quarry was discovered in 1909 by the Smithsonian Institute's Charles Doolittle Walcott (1850–1927). The Cambrian Burgess Shale (505 Ma, Miaolingian) crops out in the quarry and the lagerstätte is the nexus of ongoing vigorous debate about fossil preservation (including taphonomy and diagenesis), taxonomy, classification, phylogeny, and the origin of phyla and baupläne. Smithsonian Institute's field crews collected from 1909–1924, and the quarry was subsequently expanded by Harvard University (1930), the Canadian Geological Survey (1966–67), and the Royal Ontario Museum (1992–2000). Approximately 250,000 fossils, including soft-bodied forms, have been collected, making the Walcott Quarry with exposures of the Middle Cambrian Burgess Shale a significant Geoheritage Site and an important representation of the Cambrian Explosion.</jats:p>