Organic Rocks - Rocks formed by the accumulation of organic material. Ex. coquina and chalk. Coal - Rock composed of lithified plant material. Structures formed during deposition Bedding - Layering of sedimentary rocks. Each bed represents a homogeneous set of conditions of sedimentation.
New beds indicate new conditions.
Most layering is parallel, but occasionally it is inclined. These inclined layers are cross beds . Examples of sedimentary environments in which cross beds form are dune fields and deltas. Graded beds occur when a mass of sediment is deposited rapidly. The bedding has the coarsest sediment at the bottom and finest at the top.