The sedimentary rock formed when water deposits tiny particles of clay in very thin flat layers is called shale.

Here's why:

* Clay: Shale is primarily composed of clay minerals, which are very fine-grained particles.

* Thin Layers: The clay particles settle in very thin, flat layers, often called laminations.

* Water Deposition: The process of deposition is usually caused by water, either in a lake, river, or ocean environment.

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