Vaneesha's Geography Report

Have Mountains Always Been Here?

vk338 — Fri, 23 Apr 2010 04:55:33 +0000

Many people, including me, think that many physical features and characteristics of the earths surface has always been there. Yes, we may think that changes occur and features alter due to weather, climate, and such things. I have always imagined that mountains have just always “been there.” Mountains, actually occur all the time. Orogenesis literally means the birth of mountains. And an orogeny is a mountain building episode that thickens continental crust over millions of years. There are three types convergent plate collisions associated with orogenesis. They are 1) Oceanic plate – continental plate collision orogenesis, 2) Oceanic plate – oceanic plate collision orogenesis, and 3) Continental plate – continental plate collision orogenesis.

In oceanic plate – continental plate collision orogenesis, folded sedimentary formations have lava building up during the collision with the continental mass. int he oceanic plate – oceanic plate – oceanic plate collision orogenesis, include deformation and metamorphism of rocks and giant intrusions. This forms chains of volcanoes. The continental plate – continental plate collision orogenesis is mechanical. During this, continental masses are folded, overthrusted, faulted, and uplifted. When crustal plates do not move smoothly past each other, stress builds up the boundaries, and when the stress is relieved, earthquakes occur. On the other hand, volcanoes form at the end of the central vent that rises from the asthenosphere through the crust into a volcanic mountain. Volcanoes can occur along subduction boundaries, sea-floor spreading, and also hot spots.

A Rock More Than A Stone

vk338 — Thu, 22 Apr 2010 17:43:56 +0000

I think many of us, including me, see rocks as just a mere rock. Not only did I learn that there are more than one type of rock, I also learned that each different type of rock has a different process of formation. So the rock cycle is one of three cycles of the geological cycle. It produces the three basic rock types found in the crust. 1) Igneous, 2) Metamorphic, and 3) Sedimentary. A rock is an assemblage of minerals – an element or combination of elements that form an inorganic natural compound – bound together. Minerals such as granite, or it may be a mass of a single mineral such as a rock salt.

Igneous rocks are formed in a molten state. They form from magma which is beneath the surface of the earth. The texture of rocks is determined by how fast or slow it cools. Sedimentary rocks are made from existing rocks or form organic materials such as bones and shells. Pieces from other rocks are moved around. There are two sources of sedimentary rocks to be transferred: 1) Clastic sediments (pieces from former rocks) and 2) Chemical sediments (minerals in a solution). The process of cementation, compaction, and hardening of sediments into rocks is call lithification. And example of a sediment rock is a limestone. Metamorphormic rocks are either igneous or sedimentary, either through physical and/or chemical changes under pressure and increased temperature.

The Formation and Breakup of Pangaea

vk338 — Thu, 22 Apr 2010 06:02:09 +0000

I would think that the world changes features such as climate, weather, biomes and such things. Never did it occur to me that the earth’s structure continues to change right before our very eyes. Though the changes made are very precise and unnoticeable to human eyes until it is researched on. The processes of sea-floor spreading and subduction (where two plates collide and the less denser oceanic crust dives beneath the less dense continental plate) that produce the formation and break-up of Pangaea explain the young age of the Earth.

There are three types of plate boundaries. 1) Divergent 2) Convergent and 3) Transform. Divergent boundaries are when sea floor opens up in the center and material from the mantle forms a new sea flow and crustal plates spread apart. Convergent boundaries are collision zones where the crust is compressed and then lost. And then finally transform boundaries occur when plates slide literally past one another at right angles to a sear floor spreading center. Pressures resulting from tectonics, gravity, and weight of overlying material can lead to deformation. Deformations happen when we consider one of the following: 1) Composition of material, or 2) Amount of pressure on the rock.

Were All The Continents Once Joined Together?

vk338 — Thu, 22 Apr 2010 05:27:38 +0000

If you look closely to a world map, you will notice that many of the large continents seem as though they are pieces to a jigsaw puzzle. It is believed that all these continents were once joined together which we know as “Pangaea”. Pangaea is the supercontinent formed by the collision of all continental masses approximately 225 million years ago, named by Wegener. It is believed that some continents continue to move at the speed up 6 cm each year. This happens because of the convection currents in the asthenosphere. Here, plate tectonics come into place. This is the conceptual model that encompasses continental dirft, sea-floor spreading, and related aspects of crustal movement; accepted as the foundation of crustal tectonic processes.

Sea-floor spreading is the mechanism driving the movement of the continents; associated with upwelling flows of magma along the worldwide system of mid-ocean ridges. Mid – oceanic ridges are submarine mountain ranges that extend more than 65,000 km worldwide and are centered along sea-floor spreading centers.

Mantle convection brings magma up to the crust, crust is fractured, magma spills out and cools to form a new sea floor. And then new crust is formed. When continental crust and oceanic crust slowly collide, the denser ocean floor dives beneath the lighter continent. This is known as the subduction zone.

What Is the Eath Really Made Up Of?

vk338 — Thu, 22 Apr 2010 04:30:28 +0000

We sometimes perceive the earth as just a place that we human beings live. Many different religions and faiths have different beliefs and opinions about hot the earth came to be as it is today. The earth, is actually more than just a place to live. We do not have a direct observation about the interior structure of the earth. However through many research, we have found out that the continental (land) crust is about 12.2 km deep and the oceanic crust is about 2.5 km deep. The lithosphere (solid) is actually the earth’s crust, and that portion of the upper most mantle directly below the crust.

The earth is made up of three compositional layers: 1) Crust 2) Mantle and the 3) Core. The core has two different regions known as the inner core and the outer core. The mantle is about eighty percent of the earth’s total volume. The uppermost mantle, along with the crust, makes up the lithosphere. The lithosphere includes the crust which represents only 0.01% of the earth’s total mass. Oceanic and Continental crusts have different characteristics because of the drifting.The Continental crust is granite whereas the oceanic crust it basalt.

These are all a part of the geological cycle,. This is how we characterize the vast cycling – hydrologic, tectonic, rock, and the lithosphere. These all have their own cycles. Sets of processes can include endogenic or exogenic. Endogenic is beneath the earth’s surface and exogenic is outside the earth’s surface. For example, the hyrological cycle with be an exogenic process.

What is the difference between climate and weather?

vk338 — Thu, 22 Apr 2010 03:48:08 +0000

Many of us have always wondered why many different places on the earth have different physical features. And after geography class, I have learned that the answer to this question is Climate. Many people think that climate and weather is the same thing. They are similar in some ways and very much different in others. Climate is the consistent, long-term behavior of weather over time, including its variability. Whereas, weather is the condition of the atmosphere at any given place and time. So in other words, weather is short term atmospheric changes and is a major part of climate.

We can immediately measure weather because but we cannot measure climate immediately. Measuring climates take long periods of time. Climatic regions are locations with similar climatic conditions. We want to know about climate changes because, as we go through time, weather conditions change. We also need to keep in mind that no two places have the same climatic conditions.

An empirical classification of climate measures characteristics over long periods of time. We use moisture and temperature to describe climate. The Koppen classification system divides climates into six different types. 1) Tropical 2) Mesothermal 3) Microthermal 4) Polar 5) Arid and 6) Highland. Each of these six different types of climates have unique characteristics.

Air Pressure and Wind

vk338 — Thu, 18 Feb 2010 02:56:46 +0000

Air pressure is the pressure produced by the motion, size, and number of gas molecules that are exerted on the surfaces and are in contact within the air. The pressure of the air is influenced by factors such as temperature and density, and also the dynamic atmospheric forces. We focus on weather and climate to decide where life is distributed among the earth’s surface. Air pressure can be decreased if the air is heated up. When you heat the air up, air molecules expand, therefore there is less matter, which makes the air lighter or denser in the same amount of volume. Hotter areas have less pressure and lower density, where cooler areas have higher pressure with a higher density rate; the relationship between temperature and density.

Wind is the horizontal movement of air which is produced by differences of air pressure from place to place. The two major factors we look at when talking about wind is the speed and direction. Winds are named in the direction they are coming from, which also decides what characteristics come with the wind. Speed and direction of the wind influence pressure gradient (differences in pressure across the surface), Coriolis force (deflects the path of any object that travels in a fluid across the earth’s surface) , and frictional force (friction between the air and the ground).The pressure gradient actually decides the direction of the wind. The Coriolis force is caused by the rotation of the earth-relative motion.

Hello world!

vk338 — Wed, 10 Feb 2010 14:54:22 +0000

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