Geological Map of Erie County 1879 by Lesley, 1885
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Geological Map of Erie County 1879 by Lesley, 1885

Regular price $100.00

Geological Map of Erie County 1879, by J. Peter Lesley, from the Geological Hand-Atlas of the 67 Counties of Pennsylvania, 1885. 

This is a colored map of Erie County produced for the Second Geological Survey of Pennsylvania conducted from 1874 to 1889. It includes a key explaining which rock type is represented by each color. There are five different rocks represented on this map. They are Pocono sandstone, Catskill Oil-sand stone, Chemung Shales, Girard Shale, and Portage Flagstone. All of these are sedimentary rocks, formed through the sedimentation of minerals which were then cemented together during compaction. Sandstone is most commonly composed of feldspar and quartz, which range in sand-sized grains of .0625mm to 2mm in diameter. Flagstone is usually a flat sandstone with layered bedding planes. Shale is composed of silt-sized particles ranging in diameter from .002mm to .063mm. Pennsylvania is classified into six geological provinces, some of which are further divided into sections, based on the types of minerals found in the rock strata and their formations. Erie County contains the Central Lowlands Province, which is the smallest one in the state, along the Lake Erie Coast. The rest of the county forms part of the Northwestern Glacial Plateau section of the Appalachian Plateau Province.  

Erie County was founded on March 12, 1800. It had been part of Allegheny County after the Federal government sold the Erie Triangle to Pennsylvania in 1792. The triangle had been a disputed section of land along the shore of Lake Erie that did not fall under the charters of New York or Pennsylvania. To further complicate the problem, Massachusetts and Connecticut both claimed that the area was part of their original colonial grants. Under pressure from the federal government the states were convinced to revoke their claims. The government then sold the land to Pennsylvania, since it was the only landlocked state of the four. Erie County elected its own officials in 1803. The executive branch of the county government is run by the County Executive, and also includes the county Controller, Coroner, District Attorney, Sheriff, and Clerk. A County Council comprised of seven councilmen makes up the legislative branch. The judiciary branch contains nine judges on the Erie County Court of Common Pleas and fifteen magisterial district judges, who are managed by the district court administrator, deputy administrator, and assistant administrator. 

J. Peter Lesley (1819-1903) was a Presbyterian minister, member of the American Philosophical Society, and Pennsylvania State Geologist. He graduated from the University of Pennsylvania in 1838. Due to ill health Lesley had to take a break from his ministerial studies at Princeton Theological Seminary. During this hiatus in his studies he worked under Henry Darwin Rogers on the first Pennsylvanian Geological Survey. He returned to school in 1841, but continued to work for the survey until 1852, when he resigned because of a dispute with Rogers. That same year he left the ministry and moved back to Pennsylvania. Lesley then devoted the rest of his life to geological study. As a cartographer, he was one of the first to use contour lines to show topographical features. In 1856, he became a member of the American Philosophical Society and served as its librarian (1858-1885), secretary (1859-1887), and vice president (1887-1898). When the the sate decided to do another geological survey Lesley was hired as the director. The survey was conducted from 1874 to 1889. 

- Naomi Bean

Plate size: 8" x 9.5"
Sheet size: 9" x 11.75"
Condition: Excellent.

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