page_title: Milwaukee Formation
section_title: History and significance
hierarchical_section_title: Milwaukee Formation / History and significance
caption_attribution_description: English: Lycopod bark showing leaf scars; Middle Devonian; Milwaukee Formation; Berthelet Member; Milwaukee County, Wisconsin; UWM-GM 51372; photograph originally published in K.C. Gass, J. Kluessendorf, D.G. Mikulic, and C.E. Brett, 2019. Fossils of the Milwaukee Formation: A Diverse Middle Devonian Biota from Wisconsin, USA. Siri Scientific Press, Manchester, UK.
context_page_description: The Milwaukee Formation is a fossil-bearing geological formation of Middle Devonian age in Milwaukee County, Wisconsin. It stands out for the exceptional diversity of its fossil biota. Included are many kinds of marine protists, invertebrates, and fishes, as well as early trees and giant fungi.
  Once a prolific source of fossils, the Milwaukee Formation exposures are now mostly buried, inaccessible, on private property, or located in areas where collecting is prohibited. Most of these exposures are or were located along the Milwaukee River and Lake Michigan shore.
context_section_description: Early interest in the Milwaukee Formation was mainly of a commercial or other practical nature. Strata apparently of what would later be known as the Milwaukee Formation were utilized as early as the 1670s, when French visitors used “pitch” (natural asphalt) from the rock exposures on the shore of Lake Michigan near Milwaukee to patch their boats. The rock was later used to produce lime or building stone, and in the 1840s, Wisconsin’s first resident scientist, Increase A. Lapham, noted the natural cement potential of certain of its layers. When calcined (heated to high temperatures) and crushed, cement was produced, without requiring additives or further processing. During that time, Lapham also collected fossils from those strata, which caught the attention of James Hall, Thomas Chrowder Chamberlin and other noted American paleontologists and geologists who went on to study the biota. In 1876, the Milwaukee Cement Company began manufacturing natural cement, and soon became one of the country’s largest natural cement producers. Quarrying methods at that time required many hands to load rock into the dump cars destined for the kilns. This hands-on method was the perfect way for fossils to be detected. Several wealthy businessmen and professionals interested in acquiring large fossil collections recognized this and paid the quarry workers to set aside the best fossils. This continued until about 1911, when the cement rock was depleted, Portland Cement replaced natural cement, and the quarries were closed. Many thousands of high quality fossils were obtained this way between 1876 and 1911 for the collections of Thomas A. Greene, Edgar E. Teller, and Charles E. Monroe, and these can now be studied in numerous museums around central and eastern United States and Canada, especially the Milwaukee Public Museum, the Greene Geological Museum (University of Wisconsin-Milwaukee), the National Museum of Natural History, the Museum of Comparative Zoology, the Buffalo Museum of Science, the Field Museum of Natural History, Williams College, and the Royal Ontario Museum.
  The fossils found during and after that time indicate that the Milwaukee Formation contains one of the richest and most diverse biotas in North America coming from a single formation of its age (late Givetian), with about 250 species coming from around 100 families, at least sixteen phyla, and four kingdoms. The formation preserves fossils of marine and terrestrial organisms, including placoderm fish that were the size of great white sharks, some of the first trees, and fungi that may have reached the height of a two-story building.
caption: Bark from a lycopod tree showing leaf scars
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