Volcanic Field Features

Lava Flow.

NPS photo

The processes that created Capulin Volcano also created extraordinary forms around its base. The lava flows formed a resistant cap on the easily weathered sedimentary rocks, which protected this underlying rock from erosion while all the surrounding rock washed away. The result is the high, flat-topped mesas, such as Raton Mesa, Mesa de Maya, and Johnson Mesa.

 

Pressure Ridges.

NPS photo

At Capulin Volcano moving lava developed a crust on the surface as it cooled and in places this surface was “wrinkled” by the flowing lava beneath producing pressure ridges.

 

Lava cascades and levees formed as the lava flowed, while caves and lava tubes formed beneath the crust as the lava drained away. These lava tubes and caves are quite fragile, and so no intact lava tubes or caves may be found in the park today.

 

Tumulus.

NPS photo

Partially cooled lava, pushing through cracks like toothpaste from a tube, solidified into semi-rounded squeeze-ups called tumuli.

 

Two types of lava flows formed depending on the temperature and viscosity of the lava: fluid lava flows called pahoehoe forms smooth or ropy surfaces, while ‘A ‘a lava has a rough, jagged surface.

 

Spindle Bomb.

NPS photo

Various volcanic bombs were also formed as blobs of partly molten lava were thrown high up into the air and cooled as they fell back to the earth: breadcrust, “cow dung,” spindle, and ribbon bombs are the most common volcanic bombs at the monument.