The distribution of earthquakes and volcanoes around the world confirmed the theory of plate tectonics first proposed by Wegener. These phenomena also help categorize plate boundaries into three different types: convergent, divergent, and transform. Full description.

This lesson discusses the interior structure of the earth as defined by research on the behavior of seismic waves as they move through the layers inside of the planet. The lesson details both compositional layers as well as mechanical layers. Full description.

This module discusses the hydrologic cycle and its impacts on the planet Earth. Additionally, the module addresses connections between the hydrologic cycle, climate and the impacts humans have had on the cycle. Full description.

This module provides an overview of the biogeochemical carbon cycle. Major sources and sinks of carbon are discussed as well as the impact of human activities on global carbon levels. Full description.

This module provides an overview of the nitrogen cycle and the chemical changes that govern the cycle. Full description.

In this activity, students investigate convection as it applies to Earth processes. They will assemble a model using a bread pan to view convection in two paired cells. They will also investigate the strengths and weaknesses of the model thay have constructed and answer some questions about what they are seeing. Full description.

In this activity, candy models are used to demonstrate the features of the Earth, including its internal structure and layers. Students learn why models are essential in Earth science and answer questions about how their candy models do and do not compare with the actual Earth. Full description.

The U.S. Geological Survey (USGS) established the National Water Quality Assesment (NAWQA) program in 1985 to assess water quality conditions and trends in representative river basins and aquifers across the United States. With this report, the NRC's Water Science and Technology Board has provided advice to USGS regarding NAWQA five separate times as the program evolved from an unfunded concept to ... Full description.

The destructive force of earthquakes has stimulated human inquiry since ancient times, yet the scientific study of earthquakes is a surprisingly recent endeavor. Instrumental recordings of earthquakes were not made until the second half of the 19th century, and the primary mechanism for generating seismic waves was not identified until the beginning of the 20th century. From this recent start, a ... Full description.

Estimates of groundwater recharge and discharge rates are needed at many different scales for many different purposes. These include such tasks as evaluating landslide risks, managing groundwater resources, locating nuclear waste repositories, and estimating global budgets of water and greenhouse gasses. Groundwater Fluxes Across Interfaces focuses on scientific challenges in (1) spatial and temporal ... Full description.