Natural Resources & Societal Issues - A Geologic Perspective

William P. Leeman

Department of Geology & Geophysics
Rice University

This will be a talk in three parts - time allowing:




Geologic perspective - how does a geologist look at the world?

From space we see a Blue Planet - unique in the abundance of water at its' surface, with a dynamic atmosphere.

<-- Click on the image for an expanded view.

We know from distributions of earthquakes and volcanoes that the outer portion of the solid Earth is tectonically active and is subdivided into a number of relatively rigid plates that slide around the globe - with consequent divergent, convergent, and sometimes simple transform (strike-slip) margins (schematic diagram).

The structure of the Earth can be subdivided into a brittle outer layer (lithosphere - on the order of 100 km thick), a thick relatively ductile mantle, and a dense core - the outer part of which is molten. By comparison, the other rocky planets in the solar system have been tectonically inactive for most of their history.

New oceanic crust is being formed at divergent margins and older crust being consumed or under thrust at convergent margins.

Based on multifaceted geologic investigations by many people, the positions of most plates can be traced back through geologic time with a high degree of certainty. The plate motions can be recreated in animations to illustrate how varied was the face of the Earth through time.

This brings us to time itself, or Geologic Time, which is immense - the Earth formed roughly 4.5 billion years ago and has been evolving ever since, albeit with some irregularities in rates and intensities. Events that are exciting to geologists seem hardly to be happening to the average person.

Global climate variations through geologic time reflect oscillations in mean temperature, in part resulting from changing positions of continents and ocean circulation patterns; these, in turn, caused variations in sea level and in atmospheric CO2 content.

Key events/processes:


These and related processes resulted in magmatism, metamorphism, and ultimately in erosion and sedimentation once there was a significant hydrosphere/atmosphere. The distribution of major rock types in space and time constitutes the Geologic Record.




Natural resources

Introduction and definitions

Types of resources

Renewable vs. non-renewable (defining the system)

Geological controls on the distribution of NRs


Redistribution of the wealth: geography, climate, and other factors


Economic factors - what determines value of a resource?


Water - controversies and politics

Water resources - statistics

Aquifers - supply, quality

Water issues in Texas (mainly)

Global Issues (scarcity)

Paradigm shift in U.S.


Energy/fuel resources

Energy demands Oil production Predictions for future supplies Environmental concerns

Alternative fuels - other fossil fuels (e.g., coal), nuclear energy, renewables (e.g., solar, geothermal)



Societal implications - foreseeable problems

Long-term supply forecasts (reserves)

Adding population growth to the matrix

Rethinking resource utilization (subtitutes, recycling, conservation)

International disputes (e.g., Middle East)



The changing water paradigm
20th century water resources development driven by economic growth ethic:

We now appropriate ~54% of accessible runoff (70% by 2025?)

US: >80,000 dams and reservoirs, 90,000 Mwatts of hydroelectric capacity, >15,000 wastewater treatment plants, over $400 billion spent

Lost: >60% of inland wetlands, 50% of stream-miles polluted to some extent, many fish runs decimated (e.g., Columbia R. salmon)

Late 20th century - shift toward new water ethic? Integrity of water resources and ecosystems, fair distributions, sustainability. Also influenced by high costs of maintaining traditional infrastructure, decreasin opportunities.

US per capita water use began to decrease around 1980, with large decreases in industrial use - result of changing economics, role of 'environmental movement'. Projections of global water withdrawals have decreased with time.

Future trends

Important water-related issues:

Water brief

Small comets and the debate over the origin of water on Earth (cf. evidence for water on Mars)



A night-view of the U.S. from the Space Shuttle presents a graphic image of population density distribution based on light emissions.


P.H. Gleick (1998) The World's Water: 1998-1999. Island Press, Washington, D.C.

Page created: 3 Mar 1999