Bill-Alaska Geoscience: Module III: Landform Formation and Culture

Traveling throughout the United States one marvels at the variety of unique and beautiful landscapes created by geological forces. Some of the landscapes are so spectacular that national parks were created to preserve them for future generations. Questions arise like, how were they formed, when were they formed or how long will they last? Other questions are, who were the first people that lived here and how did they survive ?The geology involved in creating the land formations determined how the people lived, thrived and survived. The search for the geological answers created a new controversial idea. This idea in the beginning was known as continental drift. As new technologies were developed continential drift is now known as theory of plate tectonics. A German meteorologist Alfred Wegener noticed that the shapes of the coastlines of South America and Africa seemed to fit together like a puzzle. Using fossil, glacial and rock data, Wegener realized that the continents in the past have moved and at one time formed a single continent that he called Pangea. Unable to discover the mechanism involoved to explain how the continents moved his theory was rejected by most geologists. Over time and with the gathering of new evidence Wegener has been proved correct. Today his idea is know as the theory of plate tectonics. The theory states that the crust of the earth is divided into moving sections called plates. As the plates move they converge, diverge, subduct and slide by each other. The collision of plates creates transform faults, mountain ranges, volcanic activity and earthquakes . With improving technologiy geologists collect new data, analyze data and conclude that most volcanic activity and earthquakes occur along plate boundaries. The study of the ocean floor has revealed the existence of ocean trenches along subduction zones,and mid-ocean ridges along divergent zones. The mechanism that Wegener was looking for to explain why the continents move involves the subduction of plates at trenches and the diverging of plates at mid-ocean ridges. Along subducion zones plates are destroying causing volcanism and earthquakes. At mid-ocean ridges plates move apart creating new crust. The process is a huge convection current moving the continents on the plates about 1-2 in/yr.

(USGS plate motions)

Over time the continents again will form supercontinents like Pangea, and again break apart. Plate tectonics explains why coal deposits are found in the arctic, fossils of fish on Mt. Everest, glacial deposits in deserts, hydrothermal vents along ridges and the formation sulfide minerals. Once landforms are created they are slowly destroyed by the processes of weathering and erosion. This geologic recycling is known as the rock cycle. The processes within the rock cycle creates unique and beautiful landforms throughout the United States. Geologists study landforms in various stages of their development or destruction. As we increase our knowledge about plate tectonics scientists can improve the process of locating valuable minerals, fossil fuels and understanding the past geologi

c history.

No matter where we live or come from the geologic forces that created our landscapes affects our lives. Each state has it's own geologic history that has influenced how early humans survived. Each culture has tried to explain geologic events through myths, and stories passed from generation to generation. Devils Tower for example has a story that it was created by an Indian brave who turned himself into a bear and clawed the volcanic rock to create the formation that exists today. (photo Devils Tower)

Wisconsin geology includes past plate tectonic boundaries, volcanism, and glaciers. Today Wisconsin's landforms are mostly glacier related. Glaciers have given our state excellent soil for farming, abundant lakes for industry and recreation,and till deposits of gravel which in my county is the number one export. Below are examples of glacial deposits of a kame, esker, drumlin and kettle lakes.

kame, drumlin, kettle lakes

driftless area- nonglaciated- Mississippi R watershed

esker, home Iola,WI (I live on the kettle lake)

The landforms of Wisconsin have influenced our culture just as the landforms in Wainwright,AK have shaped the native Inupiat culture. Each place has dramatically different landforms. The village of Wainwright is located about 90 miles southwest of Barrow on the shores of the Chukchi Sea on the tundra. The tundra landscape is flat with year round permafrost. In summer the surface of the permafrost thaws. The melted water can not seep into the frozen ground forming many lakes. Tundra landscape features created the expansion and contraction of permafrost are polygonal forms, and ice wedges that thrust onto the surface form hills called pingos. The land cannot be used for agriculture so the local natives had to use what was given. The Inupiuts used snow to build shelters, hunted Caribou for food, skins and used bones for tools. They used the sea to provide fish and the hunting of Bowhead whales. Other mammals(seals,wolves,polar bears, walrus) were also hunted for food and fur. The pelts are used to make warm clothing to protect the people from the extreme cold. Seal skin is used to stretch over umiaqs used in whale hunting. The people used the water from the rivers as source of freshwater for cooking, cleaning and drinking. Some other food sources used were berries and other grasses and mosses that grow on the tundra. The original natives used what was given and survived. Today the traditions continue. Whale hunting, fishing and Caribou continue to provide food for the village.

Wainwright coastline Wainwright tundra and lagoon