| 41. | The original volcanic plugs have yet to be discovered, due to the considerable amount of erosion this rock layer has experienced.
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| 42. | The Pico C�o Grande ( Great Dog Peak ) is a landmark volcanic plug peak, located at in southern S�o Tom?
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| 43. | Dumbarton Rock is a geological formation known as a " volcanic plug ", formed by prehistoric build up of igneous Basalt.
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| 44. | It is the largest among a cluster of seven steep-sided volcanic plugs associated with dikes, lava flows and remnants of cinder cones.
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| 45. | Closer to the coast is the Glasshouse Mountains, a series of volcanic plugs which were named by the explorer Captain James Cook.
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| 46. | Borgarvirki is a volcanic plug ( gosstapi ), and the Icelandic sagas mention that in earlier centuries it was used for military purposes.
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| 47. | A group of small volcanoes on the upper Bridge River, known as the Bridge River Cones, includes stratovolcanoes, volcanic plugs and lava flows.
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| 48. | It is a volcanic plug of hard alkali rhyolite that squeezed up into the vents of an ancient volcano 27 million years ago.
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| 49. | Steamboat Mountain, Oregon Buttes, Boar's Tusk volcanic plug and White Mountain are sacred sites where the tribe's holy people went to pray and fast.
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| 50. | In the Kauaeranga Valley, volcanic plugs remain, as does a lava lake that now forms the top of mined in the Coromandel gold rush.
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