Hamilton Quarry is a Late Carboniferous (Virgilian) lagerstätte near Hamilton, Kansas, United States. It has a diverse assemblage of unusually well-preserved marine, euryhaline, freshwater, flying, and terrestrial fossils (invertebrates, vertebrates, and plants). This extraordinary mix of fossils has led to the interpretation of an estuarine environment. This type of Lagerstätte is considered a Konservat-Lagerstätte (or conservation lagerstätte), due to the quality the preservation of soft tissue (skin preservation).
The lagerstätte occurs within a paleovalley that was incised into the surrounding Carboniferous cyclothemic sequence during a time of low sea level, and was then filled in during a subsequent transgression. The channel has a capping series of interbedded laminated limestones and mudstones for which are designated the Lagerstätte beds or ‘vertebrate horizon’. This facies contains a well-preserved mixed assemblage of terrestrial (conifers, insects, myriapods, reptiles), freshwater (ostracods), aquatic (amphibians, reptile), brackish or euryhaline (ostracods, eurypterids, microconchids, fish), and marine (brachiopods, echinoderms) fossils.