Some localized layers of rock contain the element iridium. Iridium is most often found in space objects such as meteoroids and asteroids. The discovery of these iridium-containing layers has been matched to which phenomena in Earth's history?
A B C D
tectonic plate separations mass species extinctions orbital path changes magnetic pole reversals
Question: Some localized layers of rock contain the element iridium. Iridium is most often found in space objects such as meteoroids and asteroids. The discovery of these iridium-containing layers has been matched to which phenomena in Earth's history?
(A) tectonic plate separations
(B) mass species extinctions
(C) orbital path changes
(D) magnetic pole reversals

Answer: (B) mass species extinctions
Answer: (A) tectonic plate separations
Question: Some localized layers of rock contain the element iridium. Iridium is most often found in space objects such as meteoroids and asteroids. The discovery of these iridium-containing layers has been matched to which phenomena in Earth's history?
(A) tectonic plate separations
(B) mass species extinctions
(C) orbital path changes
(D) magnetic pole reversals
Answer: (B) mass species extinctions