Here's a breakdown:

* Formation: Cross-bedding occurs when sediments are deposited by currents, like wind or water. These currents create ripples or dunes in the sand.

* Appearance: The layers of sediment deposited on the downwind or downstream side of these ripples or dunes are angled, resulting in the characteristic wavy or tilted layers seen in cross-bedded sandstone.

* Types: There are different types of cross-bedding, including:

* Trough cross-bedding: Found in larger-scale dunes and has a "V" shape.

* Tabular cross-bedding: Found in smaller, flatter ripples.

* Ripple cross-bedding: Found in very small-scale ripples.

* Information: Cross-bedding provides important information about the environment in which the sandstone formed. For example:

* Direction of flow: The direction of the dipping layers indicates the direction of the ancient current.

* Strength of the current: The size and shape of the cross-beds can help estimate the strength of the current.

So, those wavy features in sandstone are not just aesthetically interesting, but also hold clues about the geological history of the area!