Why in NEWS

Scientists have confirmed that a volcanic rock formation in Quebec’s Nuvvuagittuq Greenstone Belt is 4.16 billion years old, making it the oldest-known intact rock on Earth, dating back to the Hadean eon, shortly after the Earth’s formation.

Key Concepts and Definitions

Term	Explanation
Hadean Eon	Earliest period in Earth’s history (4.5–4.03 billion years ago).
Metamorphosed Basalt	Volcanic rock altered by heat and pressure, originally formed from magma.
Zircon Crystals	Oldest known mineral grains, found in Australia, dating up to 4.4 billion years.
Samarium-Neodymium Dating	A radiometric method used to determine the age of ancient rocks.

The News in Simple Terms

• A volcanic rock belt in Canada’s Quebec province has been dated to 4.16 billion years, using radioactive decay dating.
• These rocks, made of metamorphosed basalt, formed underground as magma cooled.
• They offer rare insights into Earth’s early crust, primordial oceans, and pre-life environment.
• Though zircon crystals in Australia are older (4.4 billion years), they are mineral fragments—not complete rock formations.
• The Hadean eon, once thought to be a molten hell, may have had a stable crust, shallow oceans, and the conditions for early life.

Significance of the Discovery

Insight	Implication
Oldest Intact Rock	Extends our knowledge of Earth’s earliest geological history.
Early Earth Conditions	Suggests cooler crust and water bodies existed earlier than believed.
Life’s Possible Origins	Supports the hypothesis that life may have emerged in volcanic environments.
Dating Method Reliability	Validates the use of isotopic dating (Sm-Nd) in ancient rock analysis.

In a Nutshell

Memory Code: BORN – Basalt, Oldest Rock, Radiometric dating, New Earth clue

• B – Basaltic volcanic origin
• O – Oldest intact rock ever found
• R – Radiometric dating confirms age
• N – New evidence of Earth’s early crust

Prelims Practice Questions

1. The rocks in Quebec’s Nuvvuagittuq Greenstone Belt are primarily composed of:
   A. Granite
   B. Sandstone
   C. Metamorphosed basalt
   D. Schist
2. Which radiometric method was used to date the oldest-known rock formation?
   A. Carbon-14
   B. Uranium-lead
   C. Potassium-argon
   D. Samarium-neodymium
3. The Hadean Eon refers to the time:
   A. After the Cambrian explosion
   B. When multicellular life first appeared
   C. Immediately following Earth’s formation
   D. When dinosaurs ruled the Earth

Mains Practice Questions

1. What does the discovery of ancient rocks from the Hadean eon reveal about early Earth’s geology and conditions for life? (GS-1)
2. Discuss the significance of radiometric dating techniques in understanding Earth’s early history. (GS-1)

Answer Key with Explanations

Qn	Ans	Explanation
1	C	The rocks are metamorphosed volcanic basalt, formed from underground magma.
2	D	Samarium-neodymium dating was used to confirm the 4.16 billion-year age.
3	C	The Hadean eon spans from ~4.5 to 4.03 billion years ago, post-Earth formation.