Physical Geology Lecture - Environmental Geology

Definition of environmental geology: the science of the linkages between geologic and human systems.

What is the scale of the anthropogenic influence on earth systems?

The intent here is not to evaluate whether humanities influence is a good, bad or mixed change, simply to understand a bit its extent and its character. Satellite imagery and GIS tools really allows us to get a much better hold on this.

What percent of land has been farmed?

What percent of rainforest logged? In many instances more than 50% has been logged locally. A simple visual estimate from remote imagery is complicated by fact that the grows back as parts left fallow, but what grows back is not a mature rain-forest canopy.

Image of deforestation of tropical rain forest in Bolivia from NASA Visible Earth -

One estimate: "Human footprint seen on 83% of Earth's Land" -

How many dams have been built? Each dam represents a significant local change to surface water and sediment distribution processes. Dam database -

What percentage of sediment being eroded is now due to anthropogenic activity? In places where there is a significant human population estimates are that the anthropogenic component exceeds the natural by an order of magnitude.

What percentage of sulfur released to the atmosphere comes from anthropogenic sources? Probably worth investigating more, but at least one source ( suggests over 50%.

How much carbon dioxide has been added to the atmosphere by the burning of fossil fuels or other human activities? Global Climate Change Science (link to PowerPoint lecture material).

Image from NOAA site: Quote from caption: "The colors on the map above represent concentrations in the lower atmosphere of the otherwise invisible greenhouse gas on August 1, 2008. The red patch of color centered on the savanna region of the Republic of Congo and Democratic Republic of Congo in Africa shows a large quantity of the gas released from fires people light in order to clear land."

Humanity, in aggregate, is a major geologic force with respect to surface systems. This in turn has led to the proposal to define the Anthropocene, the recent geologic time span in which humanity has wielded such influence.

Sustainability: the concept that we should manage our resources so as not to compromise the opportunities for future generations. One way to look at sustainability as a discipline is that it is similar to earth system science. Earth system science creates a disciplinary space to bridge geology, biology, atmospheric science, and other sciences as we try to understand something as complex as the earth's climate. Sustainability creates a very large disciplinary space that allows us to bring together many different disciplines to consider how to manage our world for long term benefit and good.

How are geologists and geologic knowledge useful to society?

Who hires geologists?

Website on Geoscience Careers - American Geological Institute

Wrap-up comments for the class and review.

Hopefully, this course has opened your eyes more to the wonders of the earth, so that as you live your life and wander over its surface you see more than before. In this image from the Valley of Fire in Nevada and near Las Vegas, you now have the opportunity to see an arid landscape etched into different layers of older sedimentary rocks, each with its own record of past days and eons on this earth, tilted by tectonic forces related in some fashion to continents and plates moving over the surface of the earth. It is a world that is "riduculously and insanely beautiful" (James Balog).

The rock cycle provides a framework for understanding how dynamic the earth is. A view like this from southern England becomes cliffs of chalk retreating as wave action and mass wasting eat their way into the land, only to make new beach sediment that can be solidified and uplifted to make a new landscape. The chalk itself is the result of previous sediment solidified and uplifted.

This course does not have to be, should not be, the end of your learning about the earth you live on. This is the view from a mountain top in Spitbergen (Norway) looking over a fjord, with retreating glaciers, flowing rivers of ice actively carving landscape, in the distance. Many more exotic views of and insights into the vast richness the earth has to offer await those willing.

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