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Ejecta (from the Latin: "things thrown out", singular ejectum) are particles ejected from an area. In volcanology, in particular, the term refers to particles that came out of a volcanic vent, traveled through the air or under water, and fell back on the ground surface or on the ocean floor. Ejecta can consist of:

  1. juvenile particles – (fragmented magma and free crystals)
  2. cognate or accessory particles – older volcanic rocks from the same volcano
  3. accidental particles – derived from the rocks under the volcano

In planetary geology, this term includes the debris that is ejected during the formation of an impact crater, while in astrophysics, it refers to material expelled in a stellar explosion as in a supernova or in a coronal mass ejection.[1][2][3]

A lack of impact ejecta around the planet Mars' surface feature Eden Patera was one of the reasons for suspecting it was collapsed volcanic caldera not an impact crater in the 2010s.[4]


  1. ^ Matheson, Heather; Safi-Harb, Samar (2005). "The Plerionic Supernova Remnant G21.5-0.9: In and Out" (PDF). Advances in Space Research. 35 (6): 1099. arXiv:astro-ph/0504369Freely accessible. Bibcode:2005AdSpR..35.1099M. doi:10.1016/j.asr.2005.04.050. Archived from the original (PDF) on 2012-07-17. Retrieved 2013-09-15. 
  2. ^ "The Advanced Satellite for Cosmology and Astrophysics (ASCA)". Hera.ph1.uni-koeln.de. Retrieved 2013-09-15. 
  3. ^ "ASCA". Archived from the original on 2006-05-01. 
  4. ^ Amos, Jonathan (2013-10-02). "Supervolcanoes ripped up early Mars". BBC News. Retrieved 2017-02-12.