Essays

Lithosphere

.. aturate. Loam= sand+clay. Porosity- The percentage of space betwen the particles. The larger the particles, the greater the porosity. Permeability- the time necessary for all the water to drain through particles.

The larger the particles, the greater the porosity. Retention- is a particles ability to keep water within its! elf. the greater the size of the particle, the less the retention. (due to increased surface area). Runoff- Water that flows on the surface or through the ground into streams and lakes. Excess runoff usually causes floods. It is caused when pore spaces are filled up and there is no other place for the downfall to fall.

Spring- where water is forced by gravity off the side of the mountain through a crack in an impermeable layer. Artesian Well- Where a porous layer is surrounded by two non-porous layers. When there is pressure in the non-porous layers, force is increased. This force continues to build until a crack in the earths surface opens up. At this point, the water rusheds through.

It is not effected by foral rain. The pressure is determined by the gradient of the intake to the base. Water table- the top of a saturated soil zone. A visible water table is the surface of a river or stream. It is effected by the moisture of any given area.

Zone of Saturation! – the zone which modifies the water table. When moisture income is greater than the moisture loss, the table rises. When the water table is higher than nearby streams and valleys, it forms streams and rivers. The opposite may also occur. Evapotranspiration- is the greatest when there is a lot of moisture and vegetation.

Water Cycle- 64% Evapotranspired; 11% infiltrated; 25% runoff. The exchange of water among the oceain, the air, and the land. Water vapor from land rises, turns to clouds. Clouds precipitate on land and ocean. Moisture again rises and the process continues.

Eutrophication- The last stage in the aging process of a lake when there is an overabundance of algae which decreases the oxygen level. When a lake becomes a swamp, and eventually an area of land. Hastened by nutrients of sewage. The ever so popular Water Budget- A water balance. It accounts for the income, storage, and loss of water over a certain area. Most places have a surplus for a part o! f a year (usually the cool season) and not enough water at another season (usually the warm one). Deserts have a year round deficit.

Soil moisturew usually decreases during the warm season due to high and demanding evapotranspiration. It is usually a surplus in the winter because many of the plants are dead, the angles and rays of the sun are less direct, and the days are shorter. Melting snow releases large quantities of water. In most humid areas, the annual cycle of moisturwe surplus and deficit repeats itself in much the same way year after year. Within the larger annual cycle of of income, storage and outgo are transformed into a number of smaller cycles that are repeated each time it rains.

With the passage of each storm there is a period of soil moisture recharge followed by withdrawal. Droughts or floods are a part of it. Floods (excessive surplus) runoff to rivers, extending such banks. Land is most commonly reffered to as washed away in dry regions. Radioa! ctivity (radiant)- The giving off of energy and charged particles by certain atoms. The nucleus of an atom is composed of protons and neutrons.

+ charged protons of the nucleus repel and the uncharched neutrons add mass to the nucleus. Thus the balance between the repelling and binding forces in the nuclei of some kinds of atoms ios often disturbed. (Henri Becquerel pioneered radioactivity). Thus the nuclei split apart and energy and charged particles are often given off. This is known as radioactive decay. A radioactive element decays, or loses some energy or charged particles, to form another, more stable element. Because the rate of particular elements decay have been determined, it is possible to date certain objects.

Because even a very small sample of a radioactive element contains billions of charged particles, the average rate of decay can be determined. Once this average is found, calculations can be made to find out the amount of time necessary for one half! of the element to decay. This time is called half life. Carbon14 data is easy to recognize the age of a certain object. Radiocarbon is continuously forming in the Earths upper atmosphere.

This happens naturally as nitrogen atoms (14N) are hit by high-energy cosmic rays. Cosmic rays are streams of fast moving particles from atoms that reach the earth from space. Once the c14 atoms are formed, they can unite with oxygen to form carbon dioxide. The radiocarbon dating method is used in that, for example, 14CO2 enters a living tree in a certain amount. When the tree dies and decays, the amount of C14 in the wood decreases.

Scientists could then determine the date by measuring the ratio of the two. Ahh! The time line!- Principle of superposition- The idea that the oldest layer of rocks in a series is the one on bottom. Principle of Uniformitarianism- The idea that the same processes that affect the earth today also affected the earth in the past. (James Hutton) Fossi! l Correlation- Matching rock layers by using fossils that are characteristic of particular layers. (William Smith).

Correlated series of ages matched obtained locally. Geologic Time Scale- A scale representing the major eras, epochs, and periods. Era- largest division of time units. Period- division of era. Epoch- division of period.

Man cam toward the end, mammal life in middle, etc. Earthquake- a dramatic shifting of the Earths crust. It is usually reflected by movements of the lava below the crust or continental movement in general. When earthquakes are finished, they usually shift back into place and thus form aftershocks. They may continue for months after the original shock.

One way that energy travels through matter is waves. One way that energy leaves an earthquake is through seismic waves. Seismic waves radiate from the focus, or point of origin. Seismic waves are not very high. Because most of the the waves are short it is necessary to develo sensi! tive instruments. There are different types of seismic waves compressional or P waves.

When a compressional, individual particles move back and forth. The action is like the contraction and expansion of a spring. P waves travel at thousands of miles per hour. P waves can travel through gases, solids, and liquids. A shear or S wave are slower cause individual rock particles to move.

Such waves cannot pass through liquids or gases. P and S waves travel through the earth. Love waves have no movement and produce a shearing motion in the ground. Rayleigh Waves- pass through surface rocks and produce both horizontal and vertical motions. The following are the most responsible for earthquake destruction. Seismologist- earthqiuake studier.

Magnitude- the amount of energy released at the quakes focus. Richter Scale- describes intensity and magnitude of quake. Modified Mercalli Scale of Earthquake Intensity. Measures the damage of earthquake and its effects on stud! ents. 6 or higher on Richter scale is significant. P waves come way before S waves.