Why do you think raindrop impressions are more likely to be preserved in fine- grained sedimentary rock rather than coarse- grained sedimentary rocks?

Answer 1

Vary fine sediments, such as mud, will crater when struck by raindrops. If the viscosity is not decreased by too much rainfall or influx of water, the raindrop impressions will be preserved when the mud dries. If subsequent sedimentation over the dried mud is rapid, the dried mud will not have time enough to dissolve by the influx of additional moisture. Thus the imprints may survive eventual lithification into rock.

Coarser sediments would involve larger mineral and rock particle sizes and more pore space than finer, less porous sediments. The larger particles, and greater porosity would not be conducive to the creation of raindrop impressions or their preservation, as the drop would not cause a cratering of the impacted sediment, but rather pass around and through it.

Answer 2

Fine-grained sedimentary rocks have smaller particles that can fill in and support the delicate raindrop impressions, helping to preserve them. Coarse-grained rocks have larger particles with more space between them, making it harder for the impressions to be retained.