Geologists recently dated the age of Watersmeet gneiss, a type of rock in the Upper Peninsula, as the oldest in the U.S. Here's what to know.

Michigan, Minnesota and Wisconsin all feature ancient rocks known as gneisses — metamorphic rocks banded with various minerals — but an analysis determined that the gneiss in northern Michigan ...

Metamorphic rocks close metamorphic rockMetamorphic rocks ... be split into thin layers for use as roofing material. Marble is white or have swirls of colour with a crystallised structure.

The striking black-and-white striped rock, dubbed "Freya Castle," was captured ... preliminary interpretations suggest that “igneous and/or metamorphic processes could have created its stripes.” ...

The layer was subsequently covered. Around 1.7 billion years ago, by then deep underground, the layer was transformed into schist (a hard metamorphic rock) through heat and pressure.