Do these 3 things before closing this tab:
1Clear out junk files and repair common Windows errors2Scan for outdated or missing drivers - takes under a minute3Repair Windows errors before they cause bigger problemsMass extinctions happen when environmental disruption overwhelms many forms of life across broad regions or ecosystems; there is no single cause shared by every event. For the end-Cretaceous extinction, a linked set of minerals and chemical clues, together with samples from the Chicxulub crater, makes the impact explanation compelling. The end-Permian extinction, by contrast, is associated with massive volcanism and cascading changes to climate and ocean chemistry.
What can cause a mass extinction?
A mass extinction is an unusually large loss of biodiversity over a geologically short interval. It need not have one isolated trigger: a major disturbance can set off environmental changes that reinforce one another. Large-scale volcanism, for example, can release gases and other material that alter climate and ocean chemistry. Warming, oxygen loss in seawater (anoxia), and acidification can then place stress on marine ecosystems. Reviews of extinction causes emphasize that the environmental sequence and its effects can differ from event to event (2017 review of mass-extinction causes).
As an Amazon Associate I earn from qualifying purchases.
How does the end-Permian extinction compare with the impact-linked K–Pg event?
| Event | Leading evidence and interpretation | What the evidence does not establish |
|---|---|---|
| End-Permian | The crisis is associated with Siberian Traps volcanism and severe marine environmental change. A 2022 review reports that 81–94% of marine species went extinct during a rapid interval of around 60 thousand years, potentially through a combination of global warming, anoxia, and ocean acidification (Nature Reviews Earth & Environment, 2022; see also the 2012 review of end-Permian marine extinction). | This is a volcanism-and-Earth-system explanation, not evidence for an impact cause. |
| End-Cretaceous, at the Cretaceous–Paleogene (K–Pg) boundary, historically called K–T | Iridium enrichment, shocked minerals, and ejecta in boundary deposits, combined with matching material from Chicxulub crater cores, support an impact source (USGS on shocked minerals; USGS on Chicxulub and boundary evidence). | Impact evidence is strong, but the exact environmental kill sequence and the relative contribution of Deccan volcanism remain uncertain. |
How do scientists connect an impact to the K–Pg extinction?
The case rests on several kinds of evidence that fit together, not on one unusual measurement. Geologists first identify the boundary layer associated with the extinction, then examine its chemistry, minerals, and position in the rock record.
Recommended Free Tools
- Identify an unusual boundary deposit. Iridium enrichment is a geochemical clue: it marks material unlike ordinary crustal rock, but by itself it does not prove an impact.
- Look for minerals altered by extreme shock. Quartz grains can preserve planar microdeformations produced under the pressures of an impact. Their presence in boundary material supports an impact interpretation (USGS study of shock-induced quartz features).
- Check for ejected and transformed material. Spherules and altered glass are consistent with material thrown out and changed during an impact. Finding related indicators at distant sites supports a large, widespread event; a USGS study of a Wyoming boundary locality documents biological and geological evidence in this context (USGS study of the Powder River basin locality).
- Test for a source crater. Researchers compared shocked breccia clasts and melt rocks recovered from Chicxulub crater cores with material in boundary ejecta. The match links the distant crater to the global boundary layer (USGS comparison of Chicxulub samples and boundary material).
- Assess timing and fit. The crater, ejecta horizon, and extinction coincide in the geological record. Together, their timing and physical connection support a causal link more strongly than any single clue could.
What might an impact do to ecosystems?
Impact-generated dust and gases could reduce sunlight, disrupting photosynthesis and the food webs that depend on it. This provides a plausible route from a sudden impact to widespread ecological damage, but the precise sequence and relative importance of the different processes are not fully settled. NASA Science puts the qualification plainly: “Exactly how the Chicxulub impact induced the perturbation of the Earth System and the mass extinction of organisms is not yet fully understood.” (NASA Science explainer.)
#1 Best Overall
Did Deccan volcanism also contribute to the end-Cretaceous crisis?
Deccan Traps volcanism occurred during the broader end-Cretaceous interval and has been proposed as an additional source of environmental stress. Research has considered it alongside other stresses when examining the boundary event (study on environmental stress and Deccan Trap volcanism). Its possible contribution does not erase the evidence connecting Chicxulub to the boundary ejecta, but the evidence cited here does not settle how much of the extinction it caused.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.How should competing extinction explanations be evaluated?
For any proposed cause, ask whether it fits the timing of the extinction, explains independent geological clues, has an identifiable source, reaches the geographic scale of the event, and offers environmental effects consistent with the observed biological change. A hypothesis supported by one suggestive clue is weaker than one that connects timing, mechanism, and multiple independent observations. The Chicxulub case is unusually persuasive because the boundary minerals and chemistry can be linked to crater material; that does not make impact the default explanation for other mass extinctions. A review of mass-extinction causes notes that convincing impact-extinction links beyond Chicxulub are lacking (2017 review).
Quick Recap
Rank #4
- Used Book in Good Condition
Rank #3
Rank #2
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
What’s actually slowing this PC down?
Pick the symptom - the matching free tool is one click away.
