Cinder Cone Fields
Cinder cones, also known as scoria cones, can occur alone but commonly occur in groups or fields where dozens to hundreds of cones are found in one area. That is what you are viewing now.
Standing at the viewpoint, you can see the northwest flank of Newberry Volcano in the distance. Newberry is a large shield volcano that is covered with cinder cones, each of which came from a vent that opened up on the side of the volcano. As many as 400 cinder cones have been identified on the sides of Newberry. For comparison, there are about 300 cinder cones along the edges of the famous Hawaiian shield volcano Mauna Kea, and fewer than 100 cinder cones along the sides of another well-known shield volcano, Mt. Etna in Italy.
This large grouping of cones was formed during the 400,000 years of volcanic activity at Newberry. In some cases, “cone crowding” occurred when younger cinder cones formed over the top of older cones, sometimes nearly burying them. The LIDAR image below shows the multitude of cinder cones surrounding Newberry Volcano (the center of the volcano is the caldera with two lakes).
Cinder Cone Shapes
Cinder cones are typically formed when runny/foamy molten rock (magma) is spewed into the air during an eruption, and then hardens before falling back to earth as fragments called “cinders”. The bursts of magma usually occur every few minutes until eventually the cinders pile up and create a cone-shaped mound with a bowl-shaped crater on top. Cinder cones usually form rapidly, erupting for days, weeks or months, and when they are done they normally do not erupt again.
From a distance, the Newberry cinder cones may look fairly similar . . . steep-sided, symmetrical hills. However not all cinder cones are textbook-perfect, oddball shapes do occur. Non-standard shapes include:
Asymmetrical cone – an oval or elongated shape created by cinder build-up on the downwind side of the cone.
Breached cone – an amphitheater or horseshoe shape created when a lava flow breaks out the side of the cinder cone.
Secant cone – a bisected-cone shape created when lava flows break out two sides of the cinder cone.
Twin cone – a double-crater shape created when the position of the underlying vent is altered during the eruption.
Nested cone – created when the power of the eruption varies.
Eroded cone – on young cones, a bowl-shaped crater on top marks where cinders exploded from the vent. On older cones the craters have usually eroded away, leaving a smooth top.
You can see some of these non-standard cinder cone shapes in the LIDAR image above.
Logging this Earthcache
Please email or message the cache owner with answers to the following questions:
1. According to the sign, how often does Newberry Volcano erupt?
2. How many years ago did lava pour out of Lava Butte?
3. Name three of the cinder cones on the flanks of Newberry Volcano.
4. Klawhop Butte is a cinder cone with two craters. Explain how these might have formed.
Once you have emailed your answers to us, feel free to log your find immediately - you do not need to wait for a response. Please do not post the answers to the questions within your log. Thank you!
References
Oracle Education Foundation ThinkQuest, http://www.thinkquest.org
Volcano World, http://volcano.oregonstate.edu
How Volcanoes Work, http://www.geology.sdsu.edu/how_volcanoes_work
NOVA. "Meet the Volcanoes," NOVA website, http://www.pbs.org/wgbh/nova/earth/meet-volcanoes.html (accessed June 10, 2013)
Nelson, Stephen A. Volcanic Landforms, Volcanoes and Plate Tectonics