Sedimentary rocks are characterized by layers, a feature known as bedding. Bedded rocks often contain fossils and provide a snapshot of periods of earth history. Earth movements can bend layers of sediments, producing 'wrinkles' known as folds. Earth movements can also uplift bedded sedimentary rocks, sometimes to very steep angles. The photo shows a chert (silica) nodule that formed within carbonate sediments in an ancient sea, which were then later compacted and uplifted. The carbonate sediments were compacted into the rock known as limestone.