The original plate is about 100 kilometers thick

It's between 80 and 200 km below the Earth's surface.While the asthenosphere wraps around the Earth's core as one connected region,the lithosphere is separated on top into tectonic plates.There are seven primary tectonic plates that compose the shape of the planet we know today.Like the other smaller tectonic plates,the primary plates are about 100 km thick and are composed of one or two layers:continental crust and oceanic crust.