View allAll Photos Tagged Basalt
Columnar basalt rests in front of the Computing and Engineering Building on the Cheney campus of Eastern Washington University.
While not as colorful as one would like, this piece shows off some decent banding and is a nice contrast to the red basalt matrix.
Basalt in the Holocene of Idaho, USA.
Southern Idaho’s Snake River Plain represents the track of the Yellowstone Hotspot. Yellowstone is currently located in northwestern Wyoming. In the geologic past, the center of Yellowstone volcanism was in southern Idaho, and before that, it was located in southeastern Oregon.
Eight dark-colored lava fields cover portions of the modern Snake River Plain: Shoshone Lava Field, Craters of the Moon Lava Field, Wapi Lava Field, Kings Bowl Lava Field, Cerro Grande Lava Field, North Robbers Lava Field, South Robbers Lava Field, and Hell’s Half Acre Lava Field. These lavas erupted during the late Pleistocene and Holocene, well after the Yellowstone Hotspot “migrated” to the northeast. The lavas are so young that little vegetation covers them.
Seen here is a portion of Hell's Half Acre Lava Field, which is mid-Holocene in age. The rocks are basalts and vesicular basalts.
Locality: Interstate 15 roadside rest stop hiking trail, northeast of the town of Blackfoot, eastern Snake River Plain, southeastern Idaho, USA
This wall of columnar basalt (trap rock) is the most beautiful example of this geological formation I have ever seen. Found in Seljahjallagil in Iceland.
This is part of the basalt that was removed to make the underground tunnel for the MAX light rail stop at the Washington Park Zoo, Portland, OR.
Basalt in the Holocene of Idaho, USA.
Southern Idaho’s Snake River Plain represents the track of the Yellowstone Hotspot. Yellowstone is currently located in northwestern Wyoming. In the geologic past, the center of Yellowstone volcanism was in southern Idaho, and before that, it was located in southeastern Oregon.
Eight dark-colored lava fields cover portions of the modern Snake River Plain: Shoshone Lava Field, Craters of the Moon Lava Field, Wapi Lava Field, Kings Bowl Lava Field, Cerro Grande Lava Field, North Robbers Lava Field, South Robbers Lava Field, and Hell’s Half Acre Lava Field. These lavas erupted during the late Pleistocene and Holocene, well after the Yellowstone Hotspot “migrated” to the northeast. The lavas are so young that little vegetation covers them.
Seen here is a portion of Hell's Half Acre Lava Field, which is mid-Holocene in age. The rocks are basalts and vesicular basalts.
Locality: Interstate 15 roadside rest stop hiking trail, northeast of the town of Blackfoot, eastern Snake River Plain, southeastern Idaho, USA
Material: Basalt
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Pillow basalts in the Jurassic of California, USA.
The bulbous, rounded masses of volcanic rock seen here are pillow basalts. The morphology is diagnostic of underwater lava eruptions. These rocks are part of the Franciscan Complex - they represent the top portion of Jurassic-aged oceanic crust. This basaltic crust originally formed at an ancient mid-ocean ridge and got plastered onto the edge of the North American continent along a now-inactive subduction zone. The upper portions of the subducting oceanic slab (the Farallon Plate) got scraped off to form an accretionary wedge.
The basalts have been metamorphosed into greenstone, but much of the outcrop is still dark gray to black in color.
Stratigraphy: Franciscan Complex, Jurassic
Locality: Point Bonita, southwestern tip of the Marin Peninsula, Golden Gate National Recreation Area, north of San Francisco, coastal-western California, USA
Basalt from the latest issue of Knotions. Farmhouse Yarns Andy's Merino in Pumpkin Spice. 1 skein. Yum!
Behind the millwheel is a door, the entrance to the so-called Lavakeller (lava celler).
The Lavakeller in Mendig consists of a system of caves of about three square kilometres and was once the world's largest basalt pit.
The caves were dug down to a depths of 32 metres into the cooled lava flow of the Wingertsberg volcano which erupted 200,000 years before to mine basalt for mill wheels. The lava is covered by 30 metres of loess and pumice tuffs from an eruption of the Laacher See volcano about 13,000 years ago and therefore has been minded subterraneously since the 18th century.
After the downturn of the mill wheel industry due to the introduction of steel rolls in the milling business the galleries that have constant temperature of 5 to 8 °C (41 to 46.4 °F) and an air humidity of 72 % have been used as fermenting cellars and storage cellars by up to 28 breweries from 1843. Until today Mendig has a reputation as brewer town because of those numerous breweries.
Due to the invention of the refrigerating system by Carl von Linde many breweries disappeared. The only brewery that is left nowadays brews for their own pub and for regional consumers. The former beer storage cellars are partially accessible for visitors. As many galleries already collapsed many entrances had to be locked. From time to time it happens that streets or realties subside because of the undercutting.
As the neighbouring Lava-Dome the Lavakeller is part of the "Voldano Park in the administrative district of Mayen-Koblenz. [from the German Wikipedia site]
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Basalt-Mühlrad
Hinter dem Mühlrad befindet sich eine Tür, der Eingang zum sogenannten Lavakeller.
Die Lavakeller in Mendig sind etwa drei km² große Felsenkeller und das ehemalig größte Basaltlava-Bergwerk der Welt. Sie wurden in einen erkalteten Lavastrom des vor 200.000 Jahre ausgebrochenen Wingertsbergvulkan bis in eine Tiefe von 32 m gegraben, um Basalt für Mühlsteine abzubauen. Die Lava ist von etwa 30 m Löss und Bimstuffen vom Ausbruch des Laacher-See-Vulkans vor etwa 13.000 Jahren überlagert und wurde deshalb seit dem 18. Jahrhundert unterirdisch abgebaut.
Die temperaturstabilen Stollen (5–8 °C) bei einer Luftfeuchtigkeit von 72 % wurden nach dem Niedergang der Mühlsteinindustrie aufgrund der Einführung von Stahlwalzen im Mühlenwesen ab 1843 zu Gär- und Lagerkellern für zeitweise 28 Brauereien. Mendig hat wegen dieser hohen Zahl von Brauereien bis heute den Ruf einer Bierbrauerstadt. Mit Erfindung der Kühltechnik durch Carl von Linde verschwanden viele der Brauereien wieder, heute ist nur noch eine Brauerei ortsansässig und braut für die eigene Gaststätte und Abnehmer aus der Region. Die ehemaligen Bierkeller sind teilweise für Besucher zugänglich. Da bereits viele Stollen eingestürzt sind, mussten viele Zugänge gesperrt werden. Ab und zu passiert es, dass in Mendig Straßen oder Grundstücke durch die Unterhöhlung absacken.
Die Lavakeller gehören wie der benachbarte Lava-Dome zum Vulkanpark im Landkreis Mayen-Koblenz. [Wikipedia]
The beach in the little cove next to the Maquette Harbor Light is lined with a bunch of rock that looks like this, all very dark black and mostly smooth, often with these little triangular pock marks. A lot of these rocks are very large ... the rock you see here is a massive, mostly buried boulder about six feet wide and at least 20 feet long. It looks a lot like the Battlestar Gallactica from the reboot series.
This, like that black boulder I posted from the sandstone shelf at the Au Sable Light, is volcanic basalt dating to the era of the Midcontinent Rift, 1.1 billion (with a B) years ago. These were all flood basalts resulting from massive lava flows hundreds of times larger than anything that's happened in the history of humanity, either recorded or otherwise. It's really hard to process the amount of lava that flowed here. The flows were hundreds, sometime thousands of feet thick, and they covered hundreds of square miles.
But then the rift failed and the flows cooled. One thing that happens with cooling basalt lava is that it subsides, so the center of the great flows bowed downward at the center to form a giant bowl. Over time, sediment filled the bowl and formed all the sandstone you see at places like Pictured Rocks. The glacier carved a lot of this sandstone out during the last Ice Age, but the basalt beneath was harder than the sandstone and directed the path of the ice. This is, in fact, why Lake Superior is where it is. It's all a carved out lava bowl that channeled a bunch of ice.
And those triangles? That's a characteristic of the mineralogy of basalt, which likes to fracture at 60-degree angles. This is the same thing that leads some basalt to weather into hexagonal columns. The triangles are perfect enough to look artificial, but that's just how the natural world works sometimes.