Though many living things died in the Flood, a number of extinctions occurred after the Flood. In the post-flood world, there were significant changes in climate, food supply, and temperature that would have made it difficult or impossible for some animals to survive. Thus, the dinosaurs likely died out gradually in the post-flood period. This is also consistent with the occassional reports through history of people having seen dinosaurs. It is important to understand certain terms from geology.
Sedimentary rock is rock that has formed from some kind of sediment.
In many cases it is mud or sand that has fallen out of water and then hardened to rock. Some sedimentary rock can also form from chemical and biological processes. Calcium and Carbon Dioxide can combine in water to form solid Calcium Carbonate, so this can produce the rock known as limestone. Limestone forms under water but is not related to flowing water or water carrying sediment particles. Igneous rock is basically volcanic in origin.