Which sediment type is formed by ooids presenting concentric layers around a nucleus?

• A. Nodule
• B. Pelagic Sediment
• C. Oolite Sands
• D. Sand

Answer: (C)

Ooids are tiny spherical carbonate grains that grow by adding concentric layers of calcium carbonate around a central nucleus in warm, agitated shallow seawater. When sediment contains many of these ooid grains, the material is called oolite sands. Pelagic sediment is fine material that settles in deep water, nodules are irregular cemented masses, and sand simply refers to grain size. So, the sediment formed by ooids with concentric layering is oolite sands.