Lava Beds National MonumentMostly erupted around 35,000 years ago from two vents now known as Mammot

Lava Beds National MonumentMostly erupted around 35,000 years ago from two vents now known as Mammoth and Modoc in northern California, the monument is a testament to the diverse joys of a volcanic landscape, consisting of semi desert terrain filled with a variety of volcanic features. The landscape is a perfect example of volcanic terrain, and popular with geology field trips for its many textbook quality formations visible in the field.The lava flows contain a high density of tubes formed in the fluid basalt as it crusted over, shielding the rivers of liquid lava below from cooling on contact with the open air. When the vent stopped feeding lava, the river ran out of the tube, leaving these wonderful caves behind. Some of these tubes have windows in them, where the roof has caved in, allowing ecosystems such as this one at Fern Cave to infiltrate and implant themselves. The ecosystem is fragile, so tours are limited, but plenty of wonderful photos exist.The tubes are filled with very different features to the more familiar speleothems (such as stalactites, cave pearls or bacon) found in the more usual water carved limestone caves. Lava icicles remain on the ceiling, a frozen moment of deep time recording when the river of lava ran out and the remnants dripped onto the floor below. The walls look like they are flowing, since they were covered in congealed lava river features during the life of the river. There are over 25 that can be visited.Other common features in the monument include fumaroles (old gas vents), cinder and spatter cones (formed by expelled globbets of lava that cool and solidified in a rising ring around the vent) and maars (distinctly shaped craters formed when lava meets groundwater and an underground steam explosion happens). The area lies on the Medicine Lake shield volcano, the largest in the Cascades.Over 30 lava flows exist, ranging in age from 2 million to 1100 years ago. Most are basaltic, dark fluid lava that cools into a variety of amazing shapes, and the small area that is different is made of more silica rich andesite, the prototypical subduction lava. Scattered over the surface are chunks of rhyolitic pumice, remnants of the eruption of nearby Glass Mountain some 900 years back.The park also hosts plenty of wildlife, such as pronhorn antelope, bobcats, bald eagles and kangaroo rats, all adapted to the ambient aridity. It also contains Petroglyph Point, one of the best examples of Native American parietal art, showing that humans have lived in the area for a long time. It also played host to the tragic Modoc wars of 1872-3, when a group of Native Americans famously held off the US cavalry for 5 months in a natural lava fortress called Captain Jack’s Stronghold while resisting their forced expulsion from their traditional lands onto a reservation. The monument was established in 1925 and has been a very popular tourist destination ever since.LozImage credit: David E Burnell/Nature’s Best Photography competitionhttp://www.atlasobscura.com/places/lava-beds-national-monumenthttp://www.npca.org/parks/lava-beds-national-monument.htmlhttp://www.molossia.org/volcanology/lavabeds.htmlhttp://www.visitcalifornia.com/Must-Sees/Go-Underground-at-Lava-Beds-National-Monument/ -- source link

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