Editing Yellowstone Caldera (section)

==== Post-collapse rhyolites ====
Post-collapse rhyolites likely erupted shortly after the Lava Creek Tuff.{{sfn|Christiansen|Lowenstern|Smith|Heasler|2007|p=7}} The subaerial post-collapse silicic rocks are collectively referred to as the Plateau Rhyolite,{{sfn|Christiansen|2001|p=39}} which primarily consists of lava flows.{{sfn|Christiansen|Lowenstern|Smith|Heasler|2007|p=7}} Plateau Rhyolite is divided into three intracaldera members—Upper Basin Member, Mallard Lake Member, and Central Plateau Member—and two extracaldera members—Obsidian Creek Member and Roaring Mountain Member.{{sfn|Christiansen|2001|p=40}} It is likely that rhyolitic pumice and ash were erupted during the opening of vents for each of these lava flows.{{sfn|Christiansen|Lowenstern|Smith|Heasler|2007|p=7}}
The earliest intracaldera rhyolite, the East Biscuit Basin Flow of the Upper Basin Member, is dated to {{Value|0.635|0.014|u=million years}}, followed by [[felsic]] lithic clasts of an unknown unit ({{Value|0.6|0.02|u=million years}}) in [[Yellowstone Lake]],{{sfn|Morgan|Shanks|2005|p=37}} and the North Biscuit Basin Flow ({{Value|0.580|0.040|u=million years}}).{{sfn|Till|Vazquez|Stelten|Shamloo|2019|p=3868}} The earliest extracaldera rhyolite is the Riverside Flow ({{Value|0.5258|0.0033|u=million years}}) of the Roaring Mountain Member,{{sfn|Nastanski|2005|p=47}} broadly contemporaneous with the Middle Biscuit Basin Flow ({{Value|0.527|0.028|u=million years}}).{{sfn|Till|Vazquez|Stelten|Shamloo|2019|p=3868}} Two ash-flow tuff units of the Upper Basin Member include the {{convert|35|m|ft|abbr=on}}-thick Tuff of Uncle Tom’s Trail{{sfn|Christiansen|2001|p=40}} and the {{convert|230|m|ft|abbr=on}}-thick Tuff of Sulphur Creek{{sfn|Pritchard|Larson|2012|p=209}}, the latter dated at {{Value|0.479|0.02|u=million years}}.{{sfn|Christiansen|2001|p=27}} Tuff of Sulphur Creek is at least {{convert|13|km3|mi3|abbr=on}}.{{sfn|Manley|McIntosh|2002|p=220}} These tuffs were deposited on the north flank of the Sour Creek dome.{{sfn|Christiansen|2001|p=40}} The Canyon lava flows of the Upper Basin Member erupted immediately after the Tuff of Sulphur Creek, as the ash-flow was still hot at the time of emplacement.{{sfn|Christiansen|2001|p=42}} Both the Tuff of Sulphur Creek and Canyon flows originated from a vent near Fern Lake.{{sfn|Christiansen|2001|p=42}} The two tuffs and Canyon flows have a combined magma volume of {{convert|40-70|km3|mi3|abbr=on}}.{{sfn|Balsley|Gregory|1998|p=130}}
The Dunraven Road Flow ({{Value|0.486|0.042|u=million years}}) of the Upper Basin Member overlies the Canyon flows{{sfn|Christiansen|2001|p=42}} and may have had an extracaldera vent.{{sfn|Pritchard|Larson|2012|p=226}} The Cougar Creek lava dome of the Roaring Mountain Member erupted {{Value|0.358|0.002|u=million years}} north of the caldera.{{sfn|Christiansen|Lowenstern|Smith|Heasler|2007|p=78}}
Four additional lava flows of the Obsidian Creek Member—Willow Park dome, Apollinaris Spring dome, Gardner River complex, and Grizzly Lake complex—erupted between {{Value|0.326|0.002|u=million years}} and {{Value|0.263|0.003|u=million years}},{{sfn|Christiansen|Lowenstern|Smith|Heasler|2007|p=78}} in the vicinity of [[Norris Geyser Basin]] northward toward [[Mammoth Hot Springs]].{{sfn|Christiansen|2001|p=48}} The South Biscuit Basin Flow of the Upper Basin Member erupted {{Value|0.257|0.009|u=million years}} ago.{{sfn|Till|Vazquez|Stelten|Shamloo|2019|p=3868}} The Scaup Lake Flow of the Upper Basin Member is dated to {{Value|0.244|0.009|u=million years}},{{sfn|Till|Vazquez|Stelten|Shamloo|2019|p=3868}} while the Landmark dome of the Obsidian Creek Member is {{Value|0.226|0.006|u=million years}}.{{sfn|Christiansen|Lowenstern|Smith|Heasler|2007|p=78}}

Non-explosive eruptions of [[lava]] and less-violent explosive eruptions have occurred in and near the Yellowstone caldera since the last supereruption.<ref>{{cite journal |last1=Bindeman |first1=Ilya N. |last2=Fu |first2=Bin |last3=Kita |first3=Noriko T. |last4=Valley |first4=John W. |title=Origin and Evolution of Silicic Magmatism at Yellowstone Based on Ion Microprobe Analysis of Isotopically Zoned Zircons |journal=Journal of Petrology |date=January 2008 |volume=49 |issue=1 |pages=163–193 |doi=10.1093/petrology/egm075|doi-access=free |citeseerx=10.1.1.583.1851 }}</ref><ref>{{cite web|title=Secrets of supervolcanoes|url=http://pages.uoregon.edu/bindeman/Supervolcanoes.pdf|publisher=University of Oregon}}</ref> The most recent lava flow occurred about 70,000 years ago, while a violent eruption excavated the West Thumb of Lake Yellowstone 174,000 years ago. Smaller [[steam explosion]]s occur as well. An explosion 13,800 years ago left a {{convert|5|km|abbr=on}} diameter [[volcanic crater|crater]] at Mary Bay on the edge of Yellowstone Lake (located in the center of the caldera).<ref>{{cite web| title = Introduction to hydrothermal (steam) explosions in Yellowstone| work = Yellowstone National Park| publisher = Yellowstone Net| url = http://www.yellowstone.net/hydrothermal.htm| access-date = December 31, 2008| archive-date = January 6, 2009| archive-url = https://web.archive.org/web/20090106140637/http://www.yellowstone.net/hydrothermal.htm| url-status = dead}}</ref> Currently, volcanic activity is exhibited via numerous [[geothermal areas of Yellowstone|geothermal vents]] scattered throughout the region, including the famous [[Old Faithful Geyser]], plus recorded ground-swelling indicating ongoing inflation of the underlying magma chamber.{{Citation needed|date=September 2021}}