An unconformity is a buried erosion surface. It is the surface of rock that was exposed on the Earth?s surface and was then buried by younger layers. It holds geological significance as it represents missing intervals of geological records.
In Powell?s Unconformity in Grand Canyon, more than 1 billion years? worth of rocks are missing without a trace. A new study suggested that the Grand Canyon?s geological history may be more complex than previously thought and that different parts of the site may have shifted in different ways across millennia, causing some rocks and sediments to get washed away to the Ocean.