Tài liệu VOLCANOES pptx

VOLCANOES! Volcanic eruptions are among the Earth's most powerful and destructive forces. Imagine hearing a volcano erupt thousands of miles away. Imagine looking through binoculars and seeing the top of a mountain collapse. Imagine discovering an ancient Roman city that had been buried in volcanic ash. Volcanoes are also creative forces. The Earth's first oceans and atmosphere formed from the gases given off by volcanoes. In turn, oceans and an atmosphere created the environment that made life possible on our planet. Volcanoes have also shaped the Earth's landscape. Many of our mountains, islands, and plains have been built by volcanic eruptions. [...]...Snow- and ice-capped volcanoes like Mount St Helens are especially dangerous if they erupt Much of the water in Mount St Helens' mudflows came from snow and ice melted by the heat of the eruption These mudflows were as thick... and ants survived in their underground homes Within a few weeks of the eruption deer, elk, and other animals moved in from nearby areas to take advantage of the new plants that were sprouting || Top || VOLCANOES! home || This teacher packet was originally published and printed in 1997 The online edition contains full text from the original publication Some images have been modified or added to improve... Geology U.S Geological Survey Dept of Interior U.S Department of the Interior — U.S Geological Survey — 509 National Center, Reston, VA 20192, USA URL: http:// egsc.usgs.gov /isb/pubs/teachers-packets /volcanoes/ poster/poster.html — Page Maintainer: USGS Eastern Region PSC 4 Page Contact Information: Web Administrator Last modified: 06:19:02 Tue 17 May 2005 — USGS Privacy Policy and Disclaimers — Accessibility . Some volcanoes occur in the middle of plates at areas called hotspots - places where magma melts through the plate and erupts. Why Do Volcanoes Grow? Volcanoes. cone- shaped volcanoes. (Description of Figure 5.) Shield volcanoes form from eruptions of flowing lava. The lava spreads out and builds up volcanoes