Gray's Map of the United States Showing the Principal Geological Formations by Charles H. Hitchcock, Ph.D., Professor of Geology in Dartmouth College, and published by O.W. Gray & Son in Philadelphia in 1881, is a distinctive representation of the country's geological tapestry. Depicting a spectrum of geological regions from the Ecozoic to the Volcanic, this map offers a vibrant visual guide to the diverse and ancient geological history of the United States, with each formation coded distinctly by color.
The late 19th century was a period of significant strides in geological understanding. The progression from the older, foundational rocks of the Ecozoic era to the more recent Alluvium and Volcanic formations reveals a chronological narrative of the Earth's dynamic changes. This era saw a growing appreciation for geology as not just a science of minerals and rocks, but as a lens into the deep past and the evolutionary processes that have shaped the continent.
The map's hand-coloring, achieved through the use of stencils, underscores the richness of the geological diversity presented. Each hue demarcates a unique geological era, allowing for both immediate visual appreciation and deeper study. The representation of formations such as the Silurian, Devonian, and Triassic, among others, is a testament to the multi-layered nature of the American landscape.
The collaboration between Charles H. Hitchcock, a prominent figure in the geological academia of his time, and O.W. Gray & Son, a respected Philadelphia publisher, provides this map with both scientific rigor and aesthetic elegance. A reflection of a nation's geological heritage, it stands as a beacon of the intellectual curiosity and academic dedication of the late 19th century.
O. W. Gray was a publishing firm based in Philadelphia. Later, they published as O. W. Gray & Son. They published atlases in the late nineteenth century. Gray's National Atlas was one of the most successful commercial ventures of the 1870s and one of the last to employ hand coloring on maps.