Simplify the following text for a Grade 10 native English-speaking person.
Original: The formation consists of alternating layers of limestone and shale , laid down as sediment on a shallow seabed early in the Jurassic period ( about 210 â `` 195 million years ago ) , and is one of the richest fossil locations in Britain .
Simplified: This formation consists of alternating layers of limestone and shale , laid down as sediment on a shallow seabed early in the Jurassic period ( about 210-195 million years ago ) . The cliffs are one of the richest fossil locations in Britain .