This layer is a georeferenced image of a map of Northwest Africa originally created by J. Arrowsmith in 1842. The original map appears in 'The London Atlas of Universal Geography, Exhibiting the Physical & Political Divisions of the Various Countries of the World, Constructed from Original Materials. Is most respectfully dedicated to his venerable Friend John Middleton Esqr. As a testimony of Gratitude and Esteem, By his much Obliged & Humble Servant, John Arrowsmith, F.R.G.S & R.A.S. 40 Soho Square, London. London, Pubd. by J. Arrowsmith, 10 Soho Square 1842.' The historic map layers in the Google Earth Rumsey Map Collection have been selected by David Rumsey from his large collection of historical maps, as well as some from other collections with which he collaborates. All the maps contain rich information about the past and represent a sampling of time periods, scales, and cartographic art, resulting in visual history stories that only old maps can tell. Each map has been georeferenced by Rumsey, thus creating unique digital map images that allow the old maps to appear in their correct places on the modern globe. Some of the maps fit perfectly in their modern spaces, while othersgenerally earlier period mapsreveal interesting geographical misconceptions of their time. Cultural features on the maps can be compared to the modern satellite views using the slider bars to adjust transparency. The result is an exploration of time as well as space, a marriage of historic cartographic masterpieces with innovative contemporary software tools.