MSGID: 1:317/3 63ebcc63   
   PID: hpt/lnx 1.9.0-cur 2019-01-08   
   TID: hpt/lnx 1.9.0-cur 2019-01-08   
    EPOD - a service of USRA   
      
   The Earth Science Picture of the Day (EPOD) highlights the diverse processes   
   and phenomena which shape our planet and our lives. EPOD will collect and   
   archive photos, imagery, graphics, and artwork with short explanatory   
   captions and links exemplifying features within the Earth system. The   
   community is invited to contribute digital imagery, short captions and   
   relevant links.   
      
      
    Grotta di Serracozzo Lava Tube   
      
      February 14, 2023   
      
       Emanuele_epod_DSC_4668_124801_resized_20221221_121424136 (003)   
      
       Emanuele_epod_DSC_4684_01_125320_resized_20221221_121423805 (003)   
      
      Photographer:  Emanuele  Nifosi   
      Summary Author:  Emanuele Nifosi   
      
      Earlier this winter I went on a trekking excursion on the flanks of   
       Mt. Etna to  Serra delle Concazze. Along the way, we stopped at   
      the " Grotta di Serracozzo," a  lava tube created during the   
       1971 eruption of Etna. This  grotto is 350 m (~1,150 ft) long.   
      At the entrance it’s about 3 m (10 ft) wide and 6 m (20 ft) high but   
      then narrows the further in you go. The fractured  lava walls of the   
      grotto are striking, recalling aligned and symmetrical squares. They’re   
      created by  thermal contraction.   
      
      The volcanological guide pointed out that the rock, unlike what it   
      might seem, is not wet. Rather, whenever water contacts the surface   
      rapid  oxidation occurs that alters the chemical elements contained   
      within the rock, making it appear damp. Note that as you can see in the   
      bottom photo, light and fresh air enter this grotto through several   
      natural chimneys.   
      
      Photo details: Top Photo - Nikon D700 camera; NIKKOR 35-105 lens, 35   
      mm; f/5.6; ISO 800; 1 sec. exposure; flash rear + slow (handheld).   
      Photo taken on 12 December 2022, h17:08 (UTC +1)   
      
      Bottom Photo - Nikon D700 camera; NIKKOR 35-105 lens, 35 mm; f/4; 1/80   
      sec. exposure; ISO 800. Photo taken on 12 December 2022, 5.01 pm,   
      
      
      Serra delle Concazze, Catania, Sicily, Italy Coordinates: 37.756310,   
      15.053764   
      
      
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       More...   
      
   Geology Links   
      
        *  Earthquakes   
        *  Geologic Time   
        *  Geomagnetism   
        *  General Dictionary of Geology   
        *  Mineral and Locality Database   
        *  Mohs Scale of Mineral Hardness   
        *  This Dynamic Earth   
        *  USGS   
        *  MyShake - University of California, Berkeley   
        *  USGS Ask a Geologist   
        *  USGS/NPS Geologic Glossary   
        *  USGS Volcano Hazards Program   
      
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