This website is the official time clock for the United States. Users choose from a variety of time zones (Marshall, Micronesia, Palau, Guam, Samoan, Hawaiian, Alaskan, Pacific, Mountain, Central, Eastern, Atlantic or UTC) and view the current time in that zone along with a map showing day and night across the world. A world time zone map is included for reference. Links are provided to other time-related ... Full description.

SunAngle is an on-line tool that calculates solar angles and related information for a given location, date, and time. It computes the declination of the Sun, sunrise and sunset times, azimuth of the Sun, solar time and more. Complete instructions and definitions of variables are included. Full description.

This site contains 20 questions on the topic of deserts and wind, which covers dunes, desert location and formation, and particle transportation. This is part of the Principles of Earth Science course at the University of South Dakota. Users submit their answers and are provided immediate feedback. Full description.

This site contains 29 questions on the topic of Earth's changing surface, which covers weathering and erosion. This is part of the Principles of Earth Science course at the University of South Dakota. Users submit an answer and are provided immediate verification. Full description.

TerraFly is an interactive tool that allows for visualization and manipulation of spatial data. Accessed via a standard Web browser or customized CD-ROM versions, and independent of a users' level of expertise, this system allows the integration of remotely sensed data with digital data while a user is seamlessly flying over and viewing the resulting imagery. Data currently available includes land, ... Full description.

Corpscon is a Microsoft Windows-based program, which allows users to convert coordinates between Geographic, State Plane and Universal Transverse Mercator (UTM) systems on the North American Datum of 1927 (NAD 27), the North American Datum of 1983 (NAD 83), and High Accuracy Reference Networks (HARNs). Corpscon uses the National Geodetic Survey (NGS) program Nadcon to convert between NAD 27, NAD 83 ... Full description.

This software tool converts geological data from the 1927 North American Datum (NAD) to the more current 1983 North American Datum version. Data may also be transformed from either NAD 27 or NAD 83 to be compatible with High Precision Geodetic Networks (HPGN), also known as High Accuracy Reference Networks. Links on this page explain exactly how, why, and when to use such conversions, and describe ... Full description.

This on-line tool converts between Universal Transverse Mercator and Latitude/Longitude coordinates, in either direction. This site is also linked to an online demonstration of how and why to use this tool. In addition, users may obtain a copy of the software through download or mailorder (charges may apply). Full description.

This map displays the Universal Transverse Mercator (UTM) grid across the globe. Links are provided to convert between UTM and latitude/longitude coordinates and for more details on referencing coordinates within each UTM zone. Full description.

This National Park Service (NPS) website discusses the geology of Golden Gate National Recreation Area in California. Access to this area as well as the many valleys, forests, and water features are discussed. There are park maps and photos, as well as links to visitor information and additional resources. Full description.