Weathering is a process that happens to surface rocks based on the particular environment in which the rock is located. The two types of weathering are physical and chemical. Chemical weather is a process in which the internal crystals of rocks undergo chemical changes based on environmental conditions. If rock is exposed to water over a long period of time, for instance, it breaks down and often sand and clay are the result. Depending on the type of rock, there are a number of minerals that react to oxygen, particularly ones with iron or other metals. When we see reddish rocks, we are almost certain that they have iron as a component and have undergone chemical weathering.
Weathering has a symbiotic relationship to climate -- so the degree of weathering will vary with the climate of a particular area. One example might be a rock in the arctic regions would be exposed to a far different set of temperature, moisture, and chemicals over the course of a year than one in the middle of the Sahara desert. In the mid-latitudes, though, one would expect a moderate amount of both physical and chemical weathering. Depending again on the type of rock some will be more or less susceptible than others. Granite is a common mid-latitude rock, and is both dense and heavy (molecules of components are close together). Very little of the mineral components, then, will be exposed under natural conditions, so very little chemical weathering will occur. Sandstone, however, another common mid-latitude rock, will be greatly affected by chemical weathering since it is pours.
Additionally, it is important to note that chemical weathering can be increased through materials put into the atmosphere that, when mixed with water or oxygen molecules, can fall back to earth as "acid rain" or smog particles that can damage rocks. Since the mid-latitudes are the most populace areas, those areas have the higher chance of chemically induced weathering. In addition, in mid-latitudes, humans excavate, change the landscape through mining or construction, and/or otherwise expose rocks to chemicals in ways they might not have been without human intervention.
Chemical Weathering. (2010). Think Quest. Retrieved from: http://library.thinkquest.org/
Mechanical and Chemical Weathering. (2006). retrieved from: http://www.ux1.eiu.edu/~cfjps/
Part 2 -- A river delta is a landform at the mouth of a river in which the water flows into a larger body of water -- the ocean, lake, or reservoir. They are formed from deposits of sediment that are carried by the river and over long periods, deposited along the edges of the area at the mouth. This forms three sedimentary structures: 1) The bottomset beds are created from sediment that settles out of the water and laid down as tiers or layers; 2) The foreset beds build over the bottomset beds and are the loads of larger sediments that roll along the main channel. Over time these form small piles in which slides occur, thus creating different slopes; and, 3) The Topset beds overlay the foresets and are smaller sized sediments that come from the shifts in river patterns and speed.
River deltas are formed when the sediment reaches standing water, another river that cannot move as quickly, or an inland region. Often, the deltas bring rich soil from long distances in a regular pattern and deposits these sediments along the banks during flooding or high water. The Nile River is a good example of this; rich soils are deposited annual when the Nile overflows its banks, creating a more optimum environment for agriculture. There are also different types of deltas, depending on the shape and speed of the river, the body of water the delta flows into, and the types of sediment deposited.
Humans have a large impact upon deltas, and vice versa. Humans can change delta patterns through damming or changing river flow upstream (hydroelectric power, etc.). Deltas can benefit humans by allowing sand and gravel to be quarried from the region and then used in construction. Delta regions are more prone to flooding, which can cause a negative impact to humans if building is done too close to the flood plain. In fact, some estimate that almost 80% of the world's deltas are sinking slightly and making the populations that live near vulnerable.
What is a River Delta?. (2009). Americaswetlandresources.com. Retrieved from:
McLamb, E. (November 27, 2009). Human Impact: Tens of Millions Along World's River
Deltas. Ecology Global Network. Retrieved from: http://www.ecology.com / 2009/11/27/increasingly-vulnerable-flooding/
Part 3 -- The water cycle is describes the way earth's moisture moves from ice into oceans or rivers into the atmosphere, falls as precipitation and then is continually recycled. Polar ice, glaciers and sea ice have been formed by millions of years of compressed snow and ice, then melting back into the ocean as part of the water cycle. As climate changes, more or less of the world's water is bound up by polar ice, sea ice and glaciers. Right now, glacial ice covers up about 12% of all land, but during the last ice age, the sea level was far lower than today because 1/3 of the land was tied up in glacial or polar ice. The ice tied up in this way affects global weather. Because it is white, it reflects sunlight and heat and shifts weather patterns. Additionally, air temperatures are higher above ice caps, which can cause more moisture to fall in regions in which winds move off these zones. While ice caps lock up only about 2% of all water in earth's hydrological cycle, that is about 69% of all fresh water.
There are varying views on just how much the earth is warming due to lack of long-term data in geological terms. We may be experiencing a 200-400-year warming period, or, in the extreme, fossil fuels may be warming the atmosphere more than natural. The glacial and sea ice caps are shrinking, causing more and more water to melt into the oceans, since 2003, in fact, over 200 billion tons. This could conceivably cause the sea levels to rise, flooding many coastal cities; a change in climate and marine ecology, a change in the overall salinity of the world's oceans, and because of rapid melting and stress on the earth's tectonic plates, more earthquakes. With many of the world's largest cities located on coasts, this could disrupt global transportation and supply networks, as well as devastate huge number of people. More earthquakes could also contribute to coastal devastation due to tsunamis and other environmental disasters.
Ice, Snow and Glaciers: The Water Cycle. (2012). United States Geological Society. Retrieved from: http://ga.water.usgs.gov/edu/watercycleice.html
Brown, P. (2007). Melting Ice Cap Triggering Earthquakes. The Guardian. Retrieved from:
Part 4 -- Many of the world's coasts are in crisis due to a number of factors ranging from human interaction through damming, construction and changing water patterns to natural motions from waves and weather along coastal areas. As populations rise, humans tend to remove a large number of rooted plants along deltas and rivers, which contributes to more erosion in the area, and a greater chance of flooding. For some coastal regions, in fact, the major part of their sediment is supplied by rivers. Dams built from flood control and water catchment slow or even stop sand transportation, and over use of sand for construction often leaves the delta and other areas at risk. When the rivers do not have enough sediment, they begin to erode the costs more and waters migrate inland -- for instance the sediment in the Mississippi Delta being cut in half in recent years and negatively impacting Louisiana's wetland ecology.
Humans have tried to counter sediment starvation by the artificial replenishment of beach material by dumping sand directly on beaches. This is not always economically viable, because it can cost millions of dollars and lasts only a few years. There is also a clear lack of clean sand for these projects. There have been a few positive replacement projects, for instance Miami Beach had a significant influx of sand in the late 1970s, costing about $70 million, and still portions survive today. In addition to other consequences, though, natural sand movement tends to filter pollution to a greater degree; once this natural sand movement has ended; more pollution accumulates and causes poor economic consequences for coastal resorts and tourism.
Coastal Change. (2011). U.S. Geological Society. Retrieved from: http://pubs.usgs.gov
Shore Drift. (2010). Department of Ecology -- State of Washington. Retrieved from:
Part 5- A hurricane, also known as a tropical cyclone, is a storm system that has a low-pressure center and a number of thunderstorms attached that produce strong winds and heavy rains. They are formed when water evaporates in the ocean and combines with different temperatures in the atmosphere, windstorms, and polar cold air to begin swirling and adding energy to this core. They produce high winds, torrential rain, high waves, storm surges, and even tornadoes. They develop over large bodies of warm water (usually tropical temperatures)…