Ripple marks likely indicate that a rock formed

By the action of the winds and the water.

Explanation:

The ripple marks are generally formed in the sedimentary rocks and these marks are well-formed near the shore or the coastal lands and they are marks that water makes when it rushes towards the rocks, with the impacts of the winds. And these form a  gentle slope and they are thus are steeper down the current slope. Making a different angle that depends on the shape of the sediments and hence they are commonly associated with the aeolian and the fluvial deposits and thus this method results in the generation of cross-bedded units that have an appearance of the waves in exterior crop parts and cut normal as the wave crests. They can be straight and Catenary and the Lunate etc, they also vary in the small, medium ad large side. They are normal ripples and the mage ripples ad the fluid ripples.

I'm pretty sure it's c. extremely gradual but not 100% sure though.

Light rain because storms had lightning and it started crops on fire or destroyed stuff