Strato Volcanoes Vs. Shield Volcanoes

VS.

A stratovolcano, also known as a composite volcano is a tall, conical volcano built up by many layers (strata) of hardened lava, tephra, pumice, and volcanic ash. Unlike shield volcanoes, stratovolcanoes are characterized by a steep profile and periodic, explosive eruptions. The lava that flows from stratovolcanoes typically cools and hardens before spreading far due to high viscosity. The magma forming this lava is often felsic, having high-to-intermediate levels of silica(as in rhyolite, dacite, or andesite), with lesser amounts of less-viscous mafic magma. Extensive felsic lava flows are uncommon, but have travelled as far as 15 km (9.3 mi).^[2]

Stratovolcanoes are sometimes called "composite volcanoes" because of their composite layered structure built up from sequential outpourings of eruptive materials. They are among the most common types of volcanoes, in contrast to the less common shield volcanoes. Two famous stratovolcanoes are Krakatoa, best known for its catastrophic eruption in 1883 and Vesuvius, famous for its destruction of the towns Pompeii and Herculaneum in AD79.

Gulf Currents

The clockwise flow that extends northward into the Gulf of Mexico and joins the Yucatan Current and the Florida Current is known as the Loop Current. Historically, average transport values for these three currents have been around 30 Sv (e.g. Morrison and Nowlin, 1977; Nowlin and McClellan, 1967; Schmitze and Richardson, 1968). Although recent measurements (Sheinbaum et al. 2002) contend that the mean transport is 24 Sv. Near-surface velocities approach 80 cm s^-1 in the Yucatan Current (Coats, 1992) and have been reported as high as 150 cm s^-1 (at 300 m) (Nowlin and McLellan, 1967). Additionally, the Yucatan and Florida current have been shown to be within 10% of each other's volume at any given time (Molinari and Morrison, 1988). Thus, variability in both the Loop and Yucatan currents would be expected to have a strong impact on the Florida Current as well. 

Gulf Currents,!!(:

The End....

Plate Tectonics

The progress of the earth sciences and the advancement of technologies associated with the understanding of our planet during the 1940's and 50's have led geologists to develop a new way of looking at the world and how it works. This exhibit explains the history of our new understanding of the Earth and provides a brief overview of the theories behind it.

Oceans

Forms Of Land Made, By

Lava,!(:



It is recommended that you wear comfortable socks and walking shoes or hiking boots.  Year-round the weather varies on the volcano, so be prepared for all climates, hot, damp, and cold.  Bring sunscreen and wear a hat.  We suggest bringing sweatshirts as well as a wind-breaker or raincoat or gore-tex jacket to layer on your clothes.  Although there are ample water fountains in the park, we suggest you bring water with you, especially if you will be hiking.  Don't forget your camera!  If you plan to view the lava flows after dusk, remember to bring one flashlight per person

The Water Cycle

Earth's water is always in movement, and the water cycle, also known as the hydrologic cycle, describes the continuous movement of water on, above, and below the surface of the Earth. Although the balance of water on Earth remains fairly constant over time, individual water molecules can come and go in a hurry. Since the water cycle is truly a "cycle," there is no beginning or end. Water can change states among liquid, vapor, and ice at various places in the water cycle, with these processes happening in the blink of an eye and over millions of years.!(:

Global Warming

Global warming is the increase in the average temperature of Earth's near-surface air and oceans since the mid-20th century and its projected continuation. According to the 2007 Fourth Assessment Report by the Intergovernmental Panel on Climate Change (IPCC), global surface temperature increased 0.74 ± 0.18 °C (1.33 ± 0.32 °F) during the 20th century.^[2][A] Most of the observed temperature increase since the middle of the 20th century has been caused by increasing concentrations of greenhouse gases, which result from human activity such as the burning of fossil fuel and deforestation.^[3] Global dimming, a result of increasing concentrations of atmospheric aerosols that block sunlight from reaching the surface, has partially countered the effects of warming induced by greenhouse gases.

Climate model projections summarized in the latest IPCC report indicate that the global surface temperature is likely to rise a further 1.1 to 6.4 °C (2.0 to 11.5 °F) during the 21st century.^[2] The uncertainty in this estimate arises from the use of models with differing sensitivity to greenhouse gas concentrations and the use of differing estimates of future greenhouse gas emissions. An increase in global temperature will cause sea levels to rise and will change the amount and pattern of precipitation, probably including expansion of subtropical deserts.^[4] Warming is expected to be strongest in the Arctic and would be associated with continuing retreat of glaciers,permafrost and sea ice. Other likely effects include changes in the frequency and intensity ofextreme weather events, species extinctions, and changes in agricultural yields. Warming and related changes will vary from region to region around the globe, though the nature of these regional variations is uncertain.^[5] As a result of contemporary increases in atmospheric carbon dioxide, the oceans have become more acidic, a result that is predicted to continue.^[6][7]

The scientific consensus is that anthropogenic global warming is occurring.^{[8][9][10][B]}Nevertheless, political and public debate continues. The Kyoto Protocol is aimed at stabilizing greenhouse gas concentration to prevent a "dangerous anthropogenic interference".^[11] As of November 2009, 187 states had signed and ratified the protocol.^[12]

Properties of Ocean Water

Properties of Ocean Water,(:

Temperature		Earth receives its warmth from the sun. Because the world rotates on an angle to its path around the sun, radiation is spread more evenly and seasons are experienced worldwide. Read what underwater photographers need to know about light in the sea and other physical properties.
Chemical properties		Sea water consists of salt and other minerals. They are important for life.  Visit the page with sea water properties, including dissolved gases.(4p)
Physical properties		The ocean's physical properties like temperature, salinity and density are crucial to the ways in which the ocean water moves.
Productivity		The ocean's reservoir in resources seems inexhaustible, but is it? This chapter looks at the ocean's capacity to feed humans and to recycle their wastes.
soil		Also visit our large section about soil, its properties, geology and fertility and how we are losing it, perhaps the world's foremost problem! Read how the sea suffers and degrades, and read about our revolutionary discoveries about sick seas.

go back to the oceanography contents index.