Introduction to Fluvial and Karst Processes


A cycle is a repetitive exchange, and a system is any collection of interacting objects. We've looked at the rock cycle and the hydrologic cycle, and seen that earth materials are continually changed from one rock form to another. We've seen that the earth's water moves from the ocean, to the land, and eventually back to the ocean. The earth itself is a system in that everything on it either directly or indirectly effects everything else.

In the hydrologic cycle, when the water drops onto the land, its return journey to the sea has begun. It may be diverted back into the atmosphere or it may be detained for thousands of years, but in this journey overland, it is acting upon the environment to produce change. Water in any of its forms is quite powerful.

Next to gravity, which powers running water, running water is the most important force in reducing the land surface. Erosion, the wearing away of the earth's surface by natural processes, involves agents. Agents of erosion include gravity, running water (streams), ground water, wind, wave action, and glaciers. Each of these agents produce distinctive landform features.

Recognizing and understanding these features is beneficial in human habitation of the earth. Archeologists recognize that evidence of prehistoric habitation is more likely to be found in some environments than others. For example, ancient dwellings and artifacts in Alabama are found in association with terraces along streams. Examples in our own lives include that the characteristics of the landforms influence the suitability of land for construction and development, the type of natural hazards that threaten us, and the type and quality of our outdoor recreational opportunities.

In the next set of laboratory exercises, we will be examining five of these six agents of erosion, the landforms they create and the associated processes, and some of the ways in which we might be influenced by these processes. Gravity, the most important force in reducing the land surface, powers running water, ground water, glaciers, and even some aspects of wave action. However, as an agent of erosion, it is fairly minor. Block falls and talus are common on steep, rocky slopes, creep ever present on hillslopes, but avalanches, landslides, mudflows, and slumps are not as dominant and evident on topographic maps. Thus, we will by pass those topics in favor of spending time on the more visual and "exciting" topics. Fluvial processes, the agent running water, and solution, the agents of ground water will be the focus of this lesson.


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