The Oldest Rock in the Earth's Surface

Ever wonder what is the oldest rock in the world?

And where is it located?

Its age?

Many theories about the oldest formation, oldest rock and even the oldest mineral are now being proven by radiometric dating. Some may depend on the latest research, either part of the Isua Greenstone Belt, Narryer Gneiss Terrane, Nuvvuagittuq Greenstone Belt, or the Acasta Gneiss.

Outcrop of dark tonalitic gneisses near the discovery locality of the Acasta Gneiss Complex, Northwest Territories, Canada. This picture shows the sample locality for Acasta_AG09008. Field of view is approximately 10 meters across. Photo credit: S.J. Mojzsis; Source: https://eos.org/research-spotlights/archean-rocks-acasta-gneiss-complex

The Acasta Gneiss Complex of northwestern Canada contains some of the oldest dated rocks on earth. According to Stern and Bleeker of the Geological Survey of Canada, Zircon grains from the Acasta Gneiss Complex were studied based on their U-Pb isotope systematics, to have crystallized at ~4.03 Ga. Hence, considered this as one of the few old rocks known to have survived a few hundred million years of Earth's history.

Acasta Gneiss, from the collection of Dr. Yolanda Aguilar of MGB - Marine Geological Survey Division

The Acasta Gneiss Complex is composed of the Archaean igneous and gneissic cores of ancient mountain chains that have been exposed in a glacial peneplain.

The rock is composed mostly of quartz, plagioclase, biotite and hornblende. This is also identified as tonalite gneiss.

As of today, geologists have been discovering some other metamorphic rocks that could be as old as this one. But until then, the Acasta Gneiss is the oldest rock in the earth's surface.