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Earth of fire

Actualité volcanique, Article de fond sur étude de volcan, tectonique, récits et photos de voyage

Publié par Bernard Duyck
Publié dans : #Actualités volcaniques
View over the lava field of El Malpais, seen from Sandstone Bluffs - photo Undangaray

View over the lava field of El Malpais, seen from Sandstone Bluffs - photo Undangaray

El Malpais National Monument form a high valley in central New Mexico, USA. The area is covered with black lava flows covering 344 square kilometers.

In Spanish meaning "bad lands", this volcanic field, located between 1950 and 2560 meters above sea level, has cinder cones, spatter cones, a network of long lava tunnels, some ice caves and one of the largest natural arches of the state, known as "La Ventana".

The area is a traditional point of contact between cultures Mogollon, Anasazi, Sinagua and Patayan.



Left, Location of El Malpais compared to the volcanism of the Colorado Plateau - right, left access simplified map.

 Landscape of El Malpais, the Zuni-Acoma trail - photo NPS

Landscape of El Malpais, the Zuni-Acoma trail - photo NPS

Left, Location of El Malpais compared to the volcanism of the Colorado Plateau - right, left access simplified map. Left, Location of El Malpais compared to the volcanism of the Colorado Plateau - right, left access simplified map.

Left, Location of El Malpais compared to the volcanism of the Colorado Plateau - right, left access simplified map.

The Zuni-Bandera volcanic field:

The El Malpais structures are part of the Zuni-Bandera volcanic field, the second largest volcanic field in the Basin and Range Province.

The Zuni-Bandera field covers an area of ​​2,460 square kilometers in the southeastern boundary of the Colorado Plateau, at the intersection of the basin of the Rio Grande and the Jemez alignment. Its activity s' ranges from 3.8 to 3.7 Ma and 1.7 Ma.

At the edge of El Malpais, La Ventana arch is a natural sandstone arch.

Close to Sandstone Bluffs, a viewpoint offers spectacular views of the lava ... both are close to the 117 highway.


 

La Ventana arch - photo stephen-weaver.com - Southwest desert lovers

La Ventana arch - photo stephen-weaver.com - Southwest desert lovers

El Malpais lava flows:

They are of different ages and backgrounds. The most recent is the McCarty lava flow, on the west side, dated about 3,000 years. The oldest rocks are difficult to detect because of the landfill and cover.

The cinder cones of the "Chain of Craters" approximately 600 or 700,000 years.

Mount Taylor, northeast, old is 1.5 to 3.3 Ma.

Map of lava flows and their point of origin / age - doc.El Malpais - Caving / National Park Service

Map of lava flows and their point of origin / age - doc.El Malpais - Caving / National Park Service

El Malpais - pahoehoe flows - photo Markus Manske

El Malpais - pahoehoe flows - photo Markus Manske

The structures present in Western National Monument, located in a mountainous and forested landscape, are less accessible but more spectacular than the rest of the park. Twenty-five cinder cones and the remains of a lava tube system from the Bandera crater, dating from 10,500 to 9,500 years.

"Big Tubes" are accessible by unpaved forest road that leads to the Big Four Skylight and to the Four Windows, lava tubes containing permanent ice, and a series of bridges of lava remains of a collapsed lava tube.

Adequate equipment is recommended: helmet, gloves and knee pads, fleece, waterproof and good sources of light.

El Malpais - one of the Seven Bridges, lots of snow nestled in its shadow - photo American Southwest

El Malpais - one of the Seven Bridges, lots of snow nestled in its shadow - photo American Southwest

Seven bridges:

Only short sections of the roof of lava tunnel, collapsed largely, shaped bridges amounting to fifteen feet above the floor, covered with blocks and bordered by steep walls. Some lava bridges withstand much heavy pines.

Four Windows cave - photo American southwest

Four Windows cave - photo American southwest

Four Windows cave - at the entrance of the lava tube, you can see the floor in pahoehoe lava - photo naxja.org

Four Windows cave - at the entrance of the lava tube, you can see the floor in pahoehoe lava - photo naxja.org

Four Windows cave :

So named because of the small openings in the roof near the main entrance, the Windows Four lava tube present there a small moss garden, in the area where a little light penetrates, and populated by various invertebrates.

Photo at:
http://brianleddyphoto.photoshelter.com/image/I0000BeUhYhn..eY

Ice stalagmites are formed there in the winter and can be keep, the temperature between -2 and +2 ° C.

Extensive bacterial coat, whitish to golden hues, lines the walls of the tunnel adjacent to the algal mats in the twilight zone, and cover up to 25-75% of the walls in dark area. It consists essentially of actinomycetes and is devoid of any invertebrate, due to secretion of repellents antibiotics.

Tomorrow, the Big Skylight cave.

 

Sources :

- National Park Service - El Malpais National Monument - link

- El Malpais: In the Land of Frozen Fires - A History of Occupation in El Malpais Country - by Neil C. Mangum 1990 - link

- Nature of Bacterial Communities in Four Windows Cave, El Malpais National Monument, New Mexico, USA - by Diana E. Northup & al - link 

- Science in action – Caves lime - link 

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