2021 ◽  
Vol 13 (20) ◽  
pp. 4087
Author(s):  
Maria Teresa Melis ◽  
Luca Pisani ◽  
Jo De Waele

Hundreds of large and deep collapse dolines dot the surface of the Quaternary basaltic plateau of Azrou, in the Middle Atlas of Morocco. In the absence of detailed topographic maps, the morphometric study of such a large number of features requires the use of remote sensing techniques. We present the processing, extraction, and validation of depth measurements of 89 dolines using tri-stereo Pleiades images acquired in 2018–2019 (the European Space Agency (ESA) © CNES 2018, distributed by Airbus DS). Satellite image-derived DEMs were field-verified using traditional mapping techniques, which showed a very good agreement between field and remote sensing measures. The high resolution of these tri-stereo images allowed to automatically generate accurate morphometric datasets not only regarding the planimetric parameters of the dolines (diameters, contours, orientation of long axes), but also for what concerns their depth and altimetric profiles. Our study demonstrates the potential of using these types of images on rugged morphologies and for the measurement of steep depressions, where traditional remote sensing techniques may be hindered by shadow zones and blind portions. Tri-stereo images might also be suitable for the measurement of deep and steep depressions (skylights and collapses) on Martian and Lunar lava flows, suitable targets for future planetary cave exploration.


1927 ◽  
Vol 55 (1) ◽  
pp. 51-76 ◽  
Author(s):  
G. W. Tyrrell ◽  
Martin A. Peacock

Kainozoic eruptives, preponderantly of basaltic composition, occupy parts of Scotland, Ireland, Greenland, Spitsbergen, and King Charles Land, the major part of Franz Josef Land, and the entirety of Iceland, the Faeroes, and Jan Mayen. These regions have been grouped together as the Thulean or Brito-Arctic Petrographic Province (fig. l); they represent the relics of an extensive basaltic plateau-land, the greater part of which foundered beneath the North Atlantic and Arctic Oceans in late Kainozoic times. By virtue of its size, central position, diversity, and accessibility, Iceland is perhaps the most instructive region in the whole province. The interest in that country is heightened, furthermore, by the fact that whereas in all the other regions mentioned, with the exception of Jan Mayen, vulcanicity expired before the advent of the Pleistocene and did not recur, Iceland became the theatre of a vigorous resumption of igneous activity which took place in Early-glacial times, and has continued uninterruptedly to the present day.


1999 ◽  
Vol 13 (11) ◽  
pp. 1621-1628 ◽  
Author(s):  
Nilza Maria Dos Reis Castro ◽  
Anne-Véronique Auzet ◽  
Pierre Chevallier ◽  
Jean-Claude Leprun

Author(s):  
Daniela Kröhling ◽  
Ernesto Brunetto ◽  
Gabriel Galina ◽  
M. Cecilia Zalazar ◽  
Martín Iriondo

1914 ◽  
Vol 1 (7) ◽  
pp. 296-305 ◽  
Author(s):  
E. B. Bailey

The SgÙrr of Eigg first attained to geological prominence in 1865, when Sir Archibald Geikie in his delightful account of the Scenery of Scotland offered a novel and altogether captivating theory to account for its origin [1]. According to Geikie, as all well know, the precipitous ridge of pitchstone, which culminates at its eastern extremity in the SgÙrr, is the inverse of an ancient valley sunk by a winding river in the basaltic plateau of the west. Before the development of this river channel, so the theory runs, the sources which had supplied the basalt lava of the plateau had already become extinct; but volcanic activity was not yet entirely banished from the region, and presently a great outpouring of acid lava, entering the valley, flowed for miles along its course, gradually choking it, perhaps even to the brim. The resulting pitchstone has stood the test of time much more securely than the neighbouring basalts, for while these latter have wasted to a level in general lower than that of the old valley floor, the pitchstone itself still remains in large measure unaffected, and thus furnishes a somewhat battered cast of the erstwhile hollow.


2019 ◽  
Vol 81 (3) ◽  
Author(s):  
Sol Porcel ◽  
Juan F. Saad ◽  
Carmen A. Sabio y García ◽  
Irina Izaguirre

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