lavas and more explosive eruptions 100 and 200 thousand years ago than in 1959. The weight percent of K2O and Na2O of the lava has also fluctuated throughout the years.These changes are the result of the magma changing from andesite rich lava to more basalt rich over time. The magma from 100 and 200 thousand years was very andesite rich while the magma from less than 10‚000 years is almost completely basaltic lava. When the magma was andesite rich the rocks formed were trachyte and trachyandesite. When
Premium Carbon dioxide Earth Climate change
The structure of the earth The earth has three major parts-the land part or lithosphere‚ the water part or hydrosphere and the air part or atmostpere. The lithosphere is the surface on which you live . It is also the earth solid sphere consisting mainly of massive rocks. The massive rocks form large land masses called continent and small island groups . Different land form such as mountains‚hills‚valleys‚plateaus and plains make up the lithosphere. The hydrosphere include all water forms
Premium Earth Plate tectonics
Science notes Question: What happened in the 5 mass extinctions and how did the extinctions happen? Ordovician-Silurian mass extinction Third largest mass extinction Most life was in the sea 86% of sea life went extinct Trilobites died Brachiopods died Graptolites died An ice age was blamed for this mass extinction They think climate change was the cause for this Fall in sea level Messed up the chemistry of the oceans 443 Mya End of Ordovician period Start of Silurian period Late Devonian mass
Premium Ocean Water Global warming
the earth along the midocean ridges that exist in all of the major ocean basins. The ridges are composed of volcanic mountains that erupt basalt onto the surface of the ocean and by that process create new oceanic crust. The almost constant eruption of basalt causes each side of the ridge to cool‚ crystallize‚ and move away from the ridge. Each pulse of basalt eruption causes the two sides of the rift zone to move a little farther apart. The rate of plate creation at divergent boundaries varies between
Premium Plate tectonics
molecule rearrange themselves into mineral grains as the magma cools‚ forming rock as the mineral grains grow together. There are over 700 different types of igneous rocks. Examples of igneous rocks include basalt‚ granite‚ pumice‚ obsidian‚ tuff‚ diorite‚ gabbro and andesite. Basalt forms the metamorphic rock granulite when subjected to extreme heat and pressure over time (metamorphism). Igneous rocks are classified according to the mode of occurrence‚ texture‚ minerals it contains‚ chemical
Premium Igneous rock Sedimentary rock Metamorphic rock
(Eyjafjallajökull in Iceland) and characteristic basalt “pillow lava” in underwater eruptions. In this way‚ as the plates move further apart new ocean lithosphere is formed at the ridge and the ocean basin gets wider. This process is known as “sea floor spreading” and results in a symmetrical alignment of the rocks of the ocean floor which get older with distance from the ridge crest. Evidence for this process comes from the magnetic properties of the erupted basalt. The Earth’s magnetic field has been shown
Premium Plate tectonics Atlantic Ocean
A) The quartz in the gabbro and basalt decomposes very quickly. B) The ferromagnesian minerals in the gabbro and basalt are subject to oxidation and chemical breakdown. C) The plagioclase feldspars in the granite and rhyolite decompose readily to clay minerals and iron oxides. D) The potassium feldspars and quartz in the rhyolite
Premium Oxygen Water Carbon dioxide
Jessica Guerrero Geology 110 November 30‚ 2009 Chapter 6. Weathering Describe the role of external processes in the rock cycle. External processes include weathering which is the disintegration and decomposition of rock at or near earth’s surface. Mass wasting which is the transfer of rock material downslope under the influence of gravity. And erosion‚ which is the removal of material by a mobile agent‚ usually water‚ wind or ice.. These are all called external processes because
Premium Earth Mineral Water
Introduction to the Toltecs and the Aztecs The Toltec civilization thrived in central Mexico between the 10th and mid-12th centuries CE. They continued the Mesoamerican heritage and ultimately passed it on to later civilizations‚ such as the Aztecs. Fig. 2: The Sun Stone (or The Calendar Stone). (1502-20)‚ 358 cm diameter x 98 cm depth. National Anthropology Museum‚ Mexico City‚ Mexico. The Aztecs regarded the Toltecs as a great and prosperous civilization. The Aztecs flourished between 1345 and
Premium Mesoamerica Mexico Aztec
causes convection cycles‚ which drive plate tectonics. Hot mantle rises and undergoes decompression melt due to change in pressure. New oceanic crust is created in a characteristic sequence. Studies of Ophiolites show a sequence of sediment‚ pillow basalts‚ sheeted dikes‚ and gabbro being formed as hot mantle rises and creates new crust at ridges. The theory of plate tectonics is greatly supported by discoveries made at mid-oceanic ridges. INTRODUCTION When one looks across the massive oceans
Premium Plate tectonics