You are required to retain and understand terms marked with an asterisk (*); review all others.
Tectonics: Prevailing working theory in Geology that states that the external
layer of the Earth, the lithosphere, is broken
into large rigid slabs called plates, which move independently from one
another. Energy released at plate boundaries is the main cause of earthquakes.
Plate Tectonics The horizontal movement and interactions of large fragments of lithosphere at the surface of the Earth
Earth's Interior: The energy released by an
earthquake travels through the Earth as waves. Geologists have found that
both the speed and direction of these waves change abruptly at certain
depths as the waves pass through the Earth defining distinctive layers.
The Earth's Layers: Core, Mantle
and Crust. The lithosphere,
and the asthenosphere
The Earth differs
from all other known planets because of the unique relationship between
its lithosphere and the hotter, weaker, putty-like rocks that lie immediately
below, in the asthenosphere. The lithosphere-asthenosphere
boundary (that is, the strong rock-weak rock boundary) lies in the upper
mantle and does not coincide with the compositional boundary between the
crust and the mantle.
The pH is a measure of the concentration of hydrogen ions. These are derived, for example, from the dissociation of an acid--HCl--when this is dissolved in water. The pH value is defined as the negative logarithm of the hydrogen ion concentration in mol/L. The equation is:
-log10(10^-7) pH = - (-7) pH = 7
Evolution of Photosynthesis
Life theoretically originated on Earth 3.5 to 4 billion years ago. The atmosphere was thin: composed of methane, carbon dioxide, and water vapour. Any gaseous oxygen had been used up in the combustion (or oxidation) of materials when the Earth was very hot.
The cooling water collected in pools, assimilating the nutrients from the rocks. As water evaporated, the nutrients concentrated, forming a rich soup. The first organisms would have made a good living off this food source, breaking down the complex molecules into water and carbon dioxide through respiration. Eventually, as life grew, the need arose to somehow resynthesize complex compounds, both to eat and to use for structure and function. Some organisms learned how to use the sun's energy to synthesize large molecules from small molecules. Other organisms learned to use other sources of reductive power. These organisms who have learned how to build the building blocks of life are called autotrophs, or self-feeders. Autotrophs are found in the bacterial and in the plant kingdom.
Thus the basic
reaction of photosynthesis was outlined:
|05: atmosphere The envelope of gases that surrounds the Earth.|
|06: oceanic crust The crustal rocks that underlie the world's deep ocean basins. Oceanic crust is between 4 and 7 kilometers thick and is composed mostly of dark, dense basalt|
|The Crust: The crust is the outermost and thinnest layer of the Earth. Because it is relatively cool, the crust consists of hard, strong rock. The crust under de oceans differes in thinkess from that under the continents|
|07: continental crust The crustal rocks that form the continents and continental shelves. the average thickness of continental crust is about 20 to 40 kilometers, although under mountain ranges it can be as much as 70 kilometers thick. Continents are composed primarily of light-colored, less dense granite.|
|08: asthenosphere A weak layer within the mantle, just below the lithosphere|
|09: lithosphere The tough, rocky, outermost part of the Earth, comprising the crust and the uppermost part of the mantle. The Lithosphere is made of the uppermost Mantle and the Crust. The uppermost mantle is relatively cool and consequently is hard, strong rock. In fact, its mechanical behavior is similar to that of the crust. The outer part of the Earth, including both the uppermost mantle and the crust, make up the lithosphere (Greek for "rock" layer). The lithosphere normally varies from about 75 kilometers thick beneath ocean basins to about 125 kilometers under the continents.|
|The Asthenosphere: At a depth varying from about 75 to 125 kilometers the strong, hard rock of the lithosphere gives way to the weak, plastic asthenosphere (Greek for "weak" layer). This change in rock properties occurs over a vertical distance of only a few kilometers, and is caused by the Earth's rising temperature with depth. In the asthenosphere, the temperature is hot enough that I to 2 percent of the asthenosphere is molten. In addition, because of its high temperature, the solid rock of the asthenosphere is mechanically weak and plastic. Two familiar examples of solid but plastic materials are Silly Putty TM and hot road tar. If you apply force to a plastic solid, it flows slowly. The asthenosphere extends from the base of the lithosphere to a depth of about 350 kilometers.|
|The Mantle: The mantle lies directly below the crust. It is almost 2900 kilometers thick and makes up 80 percent of the Earth's volume. Although the chemical composition may be similar throughout the mantle, Earth temperature and pressure increase with depth. These changes cause the strength of mantle rock to vary with depth, and thus they create layering within the mantle. The upper mantle consists of two layers.|
|The Core: The core is the innermost of the Earth's layers. It is a sphere with a radius of about 3470 kilometers, and is composed largely of iron and nickel. The outer core is molten because of the high temperature in that region. Near its center, the core's temperature is about 6000°C, as hot as the Sun's surface. The pressure is more than 1 million times that of the Earth's atmosphere at sea level. The extreme pressure compresses the inner core to a solid despite the fact that it is even hotter than the molten outer core.|
|10: hydrosphere The oceans, lakes, and streams; underground water; and snow and ice.|
|11: biosphere The totality of living matter on the Earth.|