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The Libre Map Project was started by Jared Benedict and around 100 additional individuals contributing money to purchase (or "liberate") a full set of 1:24K scale USGS topographic maps in Digital raster graphic form. [1] The map files were then hosted by archive.org to ensure the map data will continue to be freely available to everyone ...
TopoQuest is a free web mapping service built on open source software that provides internet-based topographic map ... topographic maps in July 2008, and USGS 1:100K ...
The maps are produced by the USGS, which encourages the distribution of their maps through business partners. TopoZone offered aerial photographs from the USGS and street maps from the United States Census Bureau. In 2007 complete coverage of Canada was added, using the topographic map series produced by Natural Resources Canada.
Ordovician rocks in Illinois are divided into three series, each separated by an unconformity; from oldest to youngest, these are the Canadian, Champlainian, and Cincinnatian series. Ordovician features in Illinois include the now-buried Glasford Structure in Peoria County , a crater caused by a meteorite impact roughly 455 million years ago.
The National Map is a significant contribution to the U.S. National Spatial Data Infrastructure (NSDI) from the Federal Geographic Data Committee (FGDC) and currently is being transformed to better serve the geospatial community by providing high quality, integrated geospatial data and improved products and services including new generation ...
The Illinois side includes Henry County, Mercer County, and Rock Island County. [4] In extreme northwestern Illinois the Driftless Zone, a region of unglaciated and therefore higher and more rugged topography, occupies a small part of the state. Charles Mound, located in this region, is the state's highest elevation above sea level.
Figure 1. This BLM map depicts the principal meridians and baselines used for surveying states (colored) in the PLSS.. The following are the principal and guide meridians and base lines of the United States, with the year established and a brief summary of what areas' land surveys are based on each.
Microsoft Research Maps (MSR Maps) was a free online repository of public domain aerial imagery and topographic maps provided by the United States Geological Survey (USGS). The site was a collaboration between Microsoft Research (MSR), Bing Maps, and the USGS. It was in operation from June 1998 to March 2016.