Editing Florissant Formation (section)

==Fossils==
[[File:Florissantia species flower.png|thumb|''[[Florissantia speirii]]'' flower<ref name="website"/>]]

The volcanic material that caused so much destruction led to the preservation of the fossils within the Florissant Formation's shales and mudstones. As the ash was deposited on the landscape, it was carried by water through streams and [[lahar]]s to the lake. The lahars then covered the base of the redwoods that were living at the time, and the trunks of the trees became harder and fossilized. Through permineralization, the precipitates that were in the ground water flowed through the tree trunks, replacing the original matter with siliceous minerals, replacing the organic matter with silica. This process of mineralization led to the preservation of the stumps of the trees.<ref name="book"/>

Within the lake itself, the volcanic deposits were periodically deposited into the lake either through direct deposition or though weathering. The volcanic material was rich in silica. Living in the lake at the time were [[diatom]]s, whose shells were also composed of silica. The influx of more silica caused the diatoms to bloom in the lake. As the population of the diatoms massively increased, the stress from the volcanic episodes at the same time caused large die-offs of the local [[biota (ecology)|biota]]. As the plants and animals died off, their leaves and bodies fell into the lake and eventually large amounts of organic matter accumulated at the bottom of the lake. This process was repeated often, possibly yearly, as the runoff from rain collected in the lake, causing cyclical [[diatom]] [[algal bloom|bloom]]s and die-offs. The diatom blooms and die-offs created layers of ash-clay deposits, called couplets, resulting in many thin layers. Each microlayer of ash and clay was compacted by overlaying sediments to create "paper shales" (usually between 0.1 and 1.0&nbsp;mm thick). Within these paper shales the best preserved fossils can be found in the formation. Based on this information, it has been estimated that the lake could have lasted 2,500 to 5,000 years, if the diatom couplets represent annual cycles.<ref name = "Harding,2000"/>

[[File:Petrified Stump P6010834.JPG|thumb|right|upright|Petrified [[redwood]] stump with visible tree rings]]

===Paleoflora===
[[File:Florissant Fossil Beds National Monument FLFO1237.jpg|thumb|Fossilised leaf preserved in fine detail]]There is a large diversity of plants in the beds of the Florissant Formation, ranging from large redwoods to microscopic pollen. The petrified forest is one of the main tourist attractions at the monument with an estimated 30 preserved stumps. They are among the largest petrified stumps in the world.{{citation needed|date=May 2021}}  The majority of the stumps have been identified as belonging to ''[[Sequoia affinis]]'', a close relative of the modern [[Sequoia sempervirens|coast redwood]] (''S. sempervirens'').<ref>{{Cite web |last=Florissant |first=Mailing Address: P. O. Box 185 |last2=Us |first2=CO 80816 Phone: 719 748-3253 Contact |title=Sequoia affinis Reconconstruction - Florissant Fossil Beds National Monument (U.S. National Park Service) |url=https://www.nps.gov/flfo/learn/nature/sequoia-affinis.htm |access-date=2022-05-05 |website=www.nps.gov |language=en}}</ref> These trees could have been as tall as {{convert|60|m|ft|abbr=on}} until they were killed by lahars suffocating the oxygen supply to their roots. [[Dendrochronology|Dendrochronological examination]] of the tree rings has resulted in estimated ages of 500–700 years old when the trees were killed and buried. Some of the stumps belong to [[angiosperms]].<ref name="book"/>
 
The Florissant Formation is also known for its fossilized leaves and the impressions they made. There are also specimens of fruits, seeds, cones, and flowers, which are all preserved in the paper shales of the formation. Most of the leaves come from trees and shrubs. Angiosperms are the dominant paleoflora, but there are also conifers present.<ref name="book"/>

Some of the cones, foliage, and pollen have been identified as coming from the sequoias. There are distinct differences in the fossilized ''Sequoia affinis'' material to the modern redwoods of California. The foliage in the fossils is thinner and the female cones are smaller than the modern examples.<ref name="book"/>
There have been more than 130 species of pollen that have been identified in the shale beds at Florissant. These species represent samples from many different habitats that were located near and around the lake, as well as farther up the valley.<ref name="book"/>

Benthic diatoms are the dominant type of siliceous algae found in the beds. These are easy to fossilize due to their silica shells. During periods of volcanism, the influxes of silica from volcanic ash lead to blooms of algae, which lead to algal mats and the exceptional preservation of the fossils. Florissant is significant in that it is one of the earliest known examples of freshwater diatoms.<ref name = "Harding,2000" />

===Fauna===
The majority of the animal fossils found at Florissant are [[invertebrate]]s, but many specimens of [[vertebrate]]s have been found. With such a large number of species identified in this location, it becomes apparent that the environment was ideal for a large range of animals to survive in the area. The great preservation of these animals gives insight into the environment that they survived in, as well as some aspects of their behavior.

====Invertebrates====
The invertebrate fossils of the Florissant are [[arthropod]]s, such as spiders, [[millipede]]s, insects, and [[ostracod]]s; and [[mollusk]]s such as clams and snails. Of these, the most significant seem to be the spiders and insects, of which over 1,500 species have been identified in the fossil beds.<ref name="book"/>

[[File:Palaeovespa florissantia.jpg|thumb|''[[Palaeovespa florissantia]]'', a fossil [[wasp]], forms the logo for Florissant Fossil Beds National Monument]]

[[Arachnid]]s are well represented in the Florissant, mostly a large variety of spiders. There have also been possible examples of [[harvestmen]] and [[Pholcidae|daddy long-legs]]. There may be some evidence for [[gall mite]]s, but no fully identified body fossils of them have been discovered yet. One unusual aspect of the spiders found in the formation is that they are not found with their legs curled in, but instead they are fully extended. This could indicate that they died in warmer temperature or acidic waters.<ref name="Thoene, 2012">Thoene, J., Dena, M., Cesar, R., & Herbert, W. (2012). Depositional setting and fossil insect preservation; a study of the late eocene florissant formation, colorado. Palaios, 27(7), 481-488.</ref>
The insects that are found in the ash-clay beds are diverse and numerous. [[Mayflies]], [[dragonflies]], [[damselflies]], [[grasshopper]]s, [[crickets]], [[katydid]]s, [[cockroach]]es, [[termite]]s, [[earwig]]s, [[web-spinner]]s, [[cicada]]s, [[snake flies]], [[lacewing]]s, [[beetle]]s, [[diptera|flies]], [[mosquito]]es, [[butterflies]], [[moth]]s, [[wasp]]s, [[bee]]s, [[ant]]s, and other insects have all been found in the Florissant.<ref>Moe, A. P., & Smith, D. M. (2005). Using pre-Quaternary [[diptera]] as indicators of paleoclimate. Palaeogeography, Palaeoclimatology, Palaeoecology, 221(3-4), 203-214.</ref> Of these, the beetles are the most diverse and dominate in number of specimens found as fossils. About 38% of the specimens found in the fossil beds are varieties of beetle. These fossils are aquatic and terrestrial insects, giving insight into the ecology and biology of the area.<ref name="book"/>

Ostracods are believed to have fed on algae on the bottom of the lake. Most of the fossil examples of ostracod come from the preserved carapaces, or feeding appendages. Only one species of ostracods has been described so far. Several freshwater mollusks have been identified, including freshwater and terrestrial. The most abundant mollusk that has been identified at Florissant is [[gastropod]]s (snails).<ref name="book"/>

====Vertebrates====
The vertebrate fossils in the Florissant are predominantly small fragments of incomplete bones. There have been a few described species of vertebrates, mostly fish, but also birds and mammals.
The fish discovered at the site include [[bowfin]]s, [[Suckerfish (disambiguation)|suckers]], [[catfish]]es, and [[pirate perch]]es. Most of these were bottom dwellers, except the perches, and many were tolerant of poor water conditions. Most of the fish have been found in the same shale layers versus other shale layers. This could indicate that there were more tolerable times for fish populations over the history of the lake than other times.<ref name="book"/>

Three examples of birds have been found in the beds, including a [[cuckoo]]. Most of the skeleton was lost, but there were still enough diagnostic features to identify the bird. There are also examples of [[Coraciidae|roller]]s and [[shorebirds]]. Other birds were described in early literature from the 19th century, but the exact identification of these samples cannot be done due to lack of information.<ref name="book"/>

[[Mammal]]s are almost non-existent in the shales, with only one specimen of a small [[opossum]] being discovered so far.  In the lower mudstone units, there are samples of broken bones of a horse, a [[brontothere]], and an [[oreodont]]. The horse would have been small, about as large as a medium-sized dog, with three toes on each foot. All this information is based on a complete lower jaw. The largest mammal that has been discovered so far is a [[brontothere]], an elephant-sized animal with a pair of thick horns on the top of its head. All of this information is based on fragmented vertebrae and small pieces of tooth enamel. The oreodont, is an extinct family that resembles modern sheep and pigs. The only oreodont specimen is a jaw fragment.<ref name="book"/> Other mammals have been described in the formation based on teeth specimens. In all, around a dozen mammalian taxa have been discovered and described in the Florissant.<ref>Worley-Georg, M., & Eberle, J. J. (2006). Additions to the chadronian mammalian fauna, florissant formation, florissant fossil beds national monument, colorado. Journal of Vertebrate Paleontology, 26(3), 685-696</ref>

Surprisingly, no [[reptile]]s or [[amphibian]]s have been recorded from Florissant, where they would have been expected. No explanation for the lack has been proposed, given the nearly 40,000 specimens from this location held by museums. The toxicity of the water due to volcanic activity could be to blame, but there are documented cases of aquatic animals in the lake.<ref name="book"/>