The site was active throughout the 1800s until, in 1878, flooding by the Missouri River collapsed a large portion of the bluff and resulted in the abandonment of the nearby town of Ionia, its namesake.

The heat generated by the bluff results from iron sulfide oxidation in carbonaceous shale when it is exposed to moisture and oxygen due to erosion.

[5] The heat reaction within the bluff primarily occurs due to the high concentration of iron sulfide (FeS2) in the Carlile shale, mainly in the form of marcasite, halotrichite, and jarosite.

Jarosite will present as vertical infillings within cracks in the shale, crystalline formations, and as approximately 6 cm (2.4 in) in diameter nodes.

Furthermore, the reaction will produce hydrons (H+) as a byproduct, which will lower the surrounding soil pH to as low as 3–5[7] and attract acidophilic bacteria that can also oxidize iron sulfide.

[5] Periodic eruptions of the Ionia Volcano occurred as erosion exposed fresh Carlile shale and iron sulfide to water, causing violent exothermic reactions.

[3] In 1896, writer William Huse, in his book The History of Dixon County, Nebraska, claimed the Arapaho Tribe also believed the site to be sacred, stating that chiefs and medicine men would perform sacrificial ceremonies at the Ionia Volcano.

[3] The expedition arrived at the Ionia Volcano on August 22, 1804, camped at the site for two days, and conversed with the local Native American tribes about the bluff's religious significance.

[10] On August 24, 1804, Captain William Clark wrote:[11] "We set out at the usual time and proceeded … to the Commencement of a blue clay bluff of 180 or 190 feet high on the L.S.

[10] In 1839, French explorer and geographer, J. N. Nicollet, traveled to the site and attempted to prove that the Ionia Volcano's heat was not volcanic in origin but rather the product of chemical reactions.

On arriving at the plateau we saw several fissures in the clay, from which issued vapor so hot that the ground in the vicinity was too warm to rest the hand on comfortably.

[1] These fears were compounded in 1877, after Nebraska experienced one of the strongest earthquakes in its recorded history; locals believed this was a sign of imminent eruption.

The New York Times reported that the collapse was partially caused by the Ionia Volcano's chemical reaction heating the banks of the Missouri River, destabilizing it.

This increased activity was limited to steam being given off from the site, believed to be the byproduct of limestone and water coming into contact, and the glow of underground fires could be seen from a distance.

[1][5] Jengo also claimed that burning bluffs were relatively commonplace along the Missouri river during the 1800s, but few are still active today, the result of most of them having been submerged by flooding.