Complex sentence: The granite was once magma that crystallized at least beneath the Earth's surface, formed by an igneous intrusion during the Precambrian, approximately 1.05 billion years ago, during the Grenville orogeny.
Split into simpler sentences: The granite was once magma that crystallized at least beneath the Earth's surface. It was formed by an igneous intrusion during the Precambrian, approximately 1.05 billion years ago, during the Grenville orogeny.