Sinkholes are common where the rock below the land surface is limestone, carbonate rock, salt beds, or rocks that can naturally be dissolved by ground water circulating through them. As the rock dissolves, spaces and caverns develop underground.
The Rocky Mountains are a series of mountain ranges in western North America, including parts of New Mexico, Colorado, Utah, Wyoming, Idaho, and Montana, as well as parts of several provinces in Canada.
The USGS is a science bureau within the United States Department of the Interior.
There are numerous web resources and videos about careers in science in the USGS. 
The term El Niño (Spanish for 'the Christ Child') refers to a warm ocean current that typically appears around Christmas-time and lasts for several months, but may persist into May or June. The warm current influences storm patterns around the globe.
The Landsat Program is a series of Earth-observing satellite missions jointly managed by NASA and the U.S. Geological Survey.
Geology is the study of the Earth. This scientific study includes how the Earth was formed, how the Earth has changed since it was formed, that materials that make up the earth, and understanding the processes that act on it.
National Land Imaging (NLI) was an interagency effort (begun in 2006) to develop a long-term plan to achieve technical, financial, and managerial stability for operational land imaging.