scholarly journals Revision of the geological map and 3D modelling of the geological structure of the Samaria Gorge Region, W. Crete

2001 ◽  
Vol 34 (1) ◽  
pp. 29 ◽  
Author(s):  
Ε. ΜΑΝΟΥΤΣΟΓΛΟΥ ◽  
Ε. ΣΠΥΡΙΔΩΝΟΣ ◽  
Α. SOUJON ◽  
V. JACOBSHAGEN

The island of Crete is situated near the front of an active plate margin. Therefore, it is of great interest in the framework of the International Continental Drilling Project (I.C.D.P.). A short review of the digital modelling methods, their applications in the geosciences and the associated advantages is also presented. The digital 3-dimensional geometric model of the geological structure of the Samaria Gorge region is based on the study of the stratigraphy and the tectonic evolution of the metamorphic rocks of the Plattenkalk group in SW Crete. Data from the geological map of Greece (Vatolakkos sheet, 1:50.000) and from the literature have been supplemented by geological mapping and structural analyses. In our study we applied interactive 3D CAD methods implemented in the integrated software package SURPAC2000. The surface geology has been draped over a digital elevation model of the topography in order to model the geometry of the subsurface structures. Two hypotheses about the geological structure of the region are examined: a) the one given by the existing geological map, which proposes a syncline structure and b) the one resulting from the combination of existing data, corrections carried out through repeated 3D simulations and new field observations. After distinguishing in the S of the study area the Trypali union, overthrusted on the Plattenkalk group, we propose an anticline structure with a NNE/SSW striking axis dipping to the NE.

2017 ◽  
Vol 1 (2) ◽  
pp. 642-660 ◽  
Author(s):  
Irmela Herzog

The aim of this contribution is on the one hand to map pre-industrial long distance roads located in a hilly region east of Cologne, Germany, as exactly as possible and on the other hand to assess the accuracy of least-cost approaches that are increasingly applied by archaeologists for prehistoric road reconstruction. Probably the earliest map covering the study area east of Cologne dates back to 1575. The map is distorted so that rectification is difficult. But it is possible to assess the local accuracy of the map and to transfer the approximate routes to a modern map manually. Most of the area covered by the 1575 map is also depicted on a set of more accurate maps created in the early 19th century and a somewhat later historical map set (ca. 1842 AD). The historical roads on these rectified historical maps close to the approximate roads were digitized and compared to the outcomes of least-cost analysis, specifically least-cost paths and accessibility maps. Based on these route reconstructions with limited accuracy, Lidar data is checked to identify remains of these roads. Several approaches for visualizing Lidar data are tested to identify appropriate methods for detecting sunken roads. Possible sunken roads detected on the Lidar images were validated by checking cross sections in the digital elevation model and in the field.


1943 ◽  
Vol 4 (12) ◽  
pp. 271-275

Walcot Gibson was born at Bromsgrove, Worcestershire, on 24 August 1864. His father was a bank manager from the north country and his mother was Cornish, and they had three sons and one daughter. Gibson was educated at the Bromsgrove School and about 1882 went to Mason College, Birmingham, now the University of Birmingham. Charles Lapworth who had distinguished himself by his great researches in the south of Scotland had just been appointed to the chair of Geology at Mason College and thirty-one years later (1913) he records that Gibson was his first geological pupil. His interest in geology and geological mapping was developed by intimate contact with Lapworth and was sustained by a coterie of ardent amateur geologists, among them Joseph Landon, Fred Cullis and C. J. Gilbert. This period clearly determined Gibson’s choice of a career. After a course at the Royal College of Science he set out in 1889 on Lapworth’s advice for South Africa where he was engaged for two years on mineral surveys in the Rand goldfields and elsewhere. From there he moved to East Africa where he was engaged for another two years on mineral surveys for the East Africa Company. He returned to this country an experienced geologist and surveyor and in 1893 he joined H.M. Geological Survey in which service he remained for thirty-two years until his retirement in 1925. This was an important period in the history of the Geological Survey for owing to strong representations that the old Survey had become obsolete both in topography and geology, the House of Commons in 1891 sanctioned a resurvey of the great South Wales Coalfield on the scale of six inches to the mile. The first mapping of that field initiated by Logan and de la Beche was on the one-inch scale and was completed about 1845, the year in which the Geological Survey was transferred from the Board of Ordnance. The enormous developments which had taken place since the original survey had far outstripped the knowledge of the geological structure of the field and new information had become urgently necessary.


2019 ◽  
Vol 20 (1) ◽  
pp. 9
Author(s):  
Fitriani Agustin ◽  
Sutikno Bronto

Remote sensing technology greatly helps to identify the various of volcano features, including active, old and ancient volcanoes. The aim of this  paper is intended to introduce various volcanic features in the Gede Volcano Complexs (GVC) and souronding area; compose volcanostratigraphy; and estimate the history of the volcanoes. The method used is a visual interpretation 9 meters spatial resolution of Digital Elevation Model (DEM) TerraSar-x image. Indonesian Stratigraphy Nomenclature Guide 1996 was implemented in vocanostratigraphy unit classification, involving Arc, Super Brigate, Brigate, Crown and Hummockly. Based on the interpretation the DEM image, volcanostratigraphic unit the Gede Volcano Complex consists of Bregade Masigit (Br. M.), which consists of Joklok (Gm.J.) and Gegerbentang (Gm.G.) Hummocs; Crown Lingkung (Kh.L.) consisting of Pangrango (Gm.P.), Situ Gunung (Gm Sg.), Cikahuripan (Gm.Ck.), Pasir Prahu (Gm.Ph) Hummocs; Gege Crown (Kh.G.), which is located in the east of Lingkung Crown. The Gede Crown consists of Gumuruh humock (Gm.Gh.), Gunung Gede lava flows (LG 1,2,3,4,5), and giant debrise avalances (gv-G). The geological mapping based volcanostratigraphy is very useful for exploration of mineral and energy resources, as well as geological hazards.Keywords : volcanostratigraphy, DEM TerraSar-x image, Gunung Gede Complexs.


2021 ◽  
Author(s):  
Pawan Thapa ◽  
Narayan Thapa

Abstract Background: The impact of flooding rises due to unplanned settlements, especially in developing and underdeveloped countries. This study tries to address these issues by mapping flood risk places and assessing their impact on population and household.Methods: This study used the dataset available in Google Earth Engine (GEE), Food and Agriculture Organization (FAO), Central Bureau Statistics (CBS), Earth Data for preparing slope, drainage density, digital elevation model, rainfall, land use map, and soil map. These maps create using GEE and QGIS through overlay analysis that has two factors. The one is influence and other slopes, and it has provided high and low value according to its role on flooding.Results: The risk assessment shows around twenty-four percent population is at higher risk, whereas more than three thousand settlements are prone to flooding. It depicts a significant increasing trend of floods in the Morang district.Conclusion: This settlement risk map can help determine the flood safe and very high-risk areas in the Morang district. It will support residential places' planning by the local government, urban planners, and community people to reduce flooding risk.


1970 ◽  
Vol 47 (2) ◽  
pp. 442-456
Author(s):  
Sammy O Ombiro ◽  
Akinade S Olatunji ◽  
Eliud M Mathu ◽  
Taiwo R Ajayi

Despite Lolgorien being one of the most active gold mining areas in Kenya, it is one of the most geologically understudied areas. To the best knowledge of the authors, Lolgorien geological map was last updated in the 1940s. Current technologies such as remote sensing allow new structural features such as faults to be easily identified. In this regard, this study employed remote sensed data to map structural features found in and around Lolgorien Subcounty, Narok, Kenya. This was done to identify any new structural features that might have been missed in the past. Shuttle Radar 152 Topography Mission Digital Elevation Model (SRTM-DEM) image was downloaded and analysed using hillshade technique. From this analysis, the research identified new structural features which were not included in the current geological map but exist on the ground. One such structural feature (fault) is located approximately at 9866237, 703601 (Universal Transverse Mercator, UTM coordinates) and trends in NW–SE direction. The study also found that most of the lineaments are concentrated in the southern part of Lolgorien area and around or at areas dominated by the banded iron formations. Petrographic analysis of the few samples collected from the area showed presence of gold, pyrite and chalcopyrite mineralisation. Keywords: SRTM-DEM, lineaments, geological structures, hillshade analysis, Lolgorien area  


2020 ◽  
Vol 22 ◽  
pp. 29-32
Author(s):  
Sushant Sapkota ◽  
Pashupati Gaire ◽  
Kabi Raj Paudyal

The study area represents a small part of the Lesser Himalaya in western Nepal and lies about 346 km west from Kathmandu. It covers 250 km area representing some parts of Gulmi and Baglung districts. The area was selected for the present study on the impression from the previous geological map that has showed some metallic mineral resources like iron, copper and lead in the region. Similarly, studies reveal that there is very complicated geological structure which raised the interest for the study. Main objective of the study was to prepare a geological map of the area in a scale of 1:25,000 and study the possible mineral deposits. An extensive geological mapping was carried out in the field covering at one data within one centimetre of the map scale and large number of samples was collected for the petrographic as well as ore genesis studies. The rocks of the region were mapped under two geological units as the Nourpul Formation (older) and the Dhading Dolomite (younger).  There are a series of folds in the area. From regional to micro-scale all folds are trending towards east-west. The Badi Gad Fault and the Harewa Khola Thrust are the regional scale thrust mapped in the area. The Badi Gad is considered as a strike-slip in nature. The Harewa Khola Thrust is probably an imbricate fault. It has propagated to the north which is out of sequence in nature. Some metallic minerals like copper and iron along with old working mines were observed during the study. Occurrences of copper and iron mineralization has been mapped and described. Present study revealed that copper mineralization is limited within the veins and boudinage forms as hydrothermal deposit while the iron is tabular and syngenetic in nature.


2021 ◽  
Author(s):  
Pawan Thapa ◽  
Narayan Thapa

Abstract Background: The impact of flooding rises due to unplanned settlements, especially in developing countries. This study tries to address these issues by mapping flood risk places and assessing their impact on population and household.Methods: This study used the dataset available in Google Earth Engine (GEE), Food and Agriculture Organization (FAO), Central Bureau Statistics (CBS), Earth Data for preparing slope, drainage density, digital elevation model, rainfall, land use map, and soil map. These maps create using GEE and QGIS through overlay analysis that has two factors. The one is influence and other slopes, and it has provided high and low value according to its role on flooding.Results: The risk assessment shows around twenty-four percent population is at higher risk, whereas more than three thousand settlements are prone to flooding. It depicts a significant increasing trend of floods in the Morang district.Conclusion: This settlement risk map can help determine the flood safe and very high-risk areas in the Morang district. It will support residential places' planning by the local government, urban planners, and community people to reduce flooding risk.


Geosciences ◽  
2018 ◽  
Vol 8 (9) ◽  
pp. 340 ◽  
Author(s):  
Marcelo Cando Jácome ◽  
Antonio Martínez-Graña

Mass movements in deformed areas of natural relief deformed by seismotectonic factors are one of the most destructive and recurrent natural hazards in the Republic of Ecuador, especially during intense rain periods, the El Niño phenomenon, or due to earthquakes such as the one that occurred on 16 April 2016 in the Ecuadorian coastline. This study proposes the application of Hydrological Model D8 and its derived morphometric parameters like slope, orientation of the slope, and curvatures, extracted from the high spatial resolution Digital Elevation Model (DEM), implemented in programs such as Rockworks 7 (gridzo), SURFER (downwards slope), ArcView (flowacc), and SAGA (curvatures) to obtain runoff flow, structural geological lineaments, and superficial deformations of the topographic relief that are the origin of erosion, superficial landslides, lateral propagation, of the rock–soil complex, mass flows, and deep gravitational deformations. This methodology has been validated in three locations with intense deformations: two in Ecuador and one in Spain. The DEM were obtained from the Ecuadorian Spatial Institute (ESI) (spatial resolution of 10 m), the Rural Technological Infrastructure and Information National System (SIGTIERRAS) (spatial resolution of 5 m), and the Council of Andalusia (spatial resolution of 5 m).


2007 ◽  
Vol 26 (1) ◽  
pp. 75-84 ◽  
Author(s):  
Eric Groessens ◽  
Marie-Claire Dyck

The career of Jean-Baptiste-Julien d'Omalius d'Halloy (1783-1875), commencing with brilliant scientific activities and proceeding to his attainment of the highest administrative and political positions, in itself demonstrates that he was an exceptional individual. His scientific career started with a long voyage through the French Empire and adjacent regions, during which he gained an understanding of the geological structure of most of Europe. The geological map he compiled based on his travel notes formed the basis of all future geological maps in the areas that he covered. After the independence of Belgium in 1830, André Dumont was made responsible for the mapping of the whole country, resulting in the publication of a 9-sheet map of Belgium in 1853 on a scale of 1:160.000. In 1878, Belgium decided to produce a more detailed map on the scale of 1:20.000, entrusting the work to Edouard Dupont., but as this appointment was controversial and the mapping at this scale was abandoned and than, the newly created Geological Survey of Belgium published a new 226-sheet map on a scale of 1:40.000. Starting from 1993, after the federalisation of the country, new geological maps of the regional states are mapped and produced.


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