Transcription: Sedimentary rock forms in layers. Those layers are often horizontal, but they are often tilted as well. Geologists call these layers strata, and since the rocks you're seeing in this video have strata in them, they're referred to as stratified rock. As you can also see in this video, the strata formed by sedimentary rock vary greatly in both appearance and thickness. As you will learn in this module and the next two modules, Details of how these strata form are a source of great controversy in geology.
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