This crag, an eye-catching expanse of gneiss rock near Tram Stop 1, makes a perch for saguaros. Cracks in the cliff face are geologic features known as joints. Dean Knuth/Arizona Daily Star ...

Discovered in 1989, the Acasta Gneiss is an outcrop of metamorphic rock dating from the earliest part of the Precambrian Era. It falls within the Hadean Period, which started with the formation of ...

Yellow Aster Gneiss. Season 5 Episode 7 | 5m 41s Video has Closed Captions | CC. Oldest North Cascades bedrock, a 400-million-year-old tale from European origins. 01/18/2024 | Expires 12/06/2025.

Plant communities with exceptional floral concentrations might trace their origins to geologic episodes occurring more than 250,000,000 years ago.

But the Acasta Gneiss is the oldest intact piece of Earth’s crust, according to Elizabeth Cottrell, chair of the department of mineral sciences at the National Museum of Natural History.

Morton gneiss (pronounced “nice”), named for the town in Renville County where it has been quarried, is one of the oldest stones on the planet: about 3.5 billion years old.

Writer Sara Maitland conjures with a rock of ages, Lewisian gneiss. Two-thirds the age of the earth, it began its journey where Antarctica is today and makes up parts of Scotland. Show more The ...