Final answer:
The bedrock in the Hamilton area is known as a Dolostone cap, which is a type of sedimentary rock characterized by its geological features such as cross-bedding and well-rounded sand grains.
Step-by-step explanation:
The bedrock in the Hamilton area is known as a Dolostone cap. This name is derived from the presence of dolostone, a type of sedimentary rock, that serves as a significant component of the region's geological makeup. Given the descriptions of multiple forms of sandstone and their features within the question context, it is clear that these are characteristic of sedimentary environments. For instance, large-scale cross-bedding and very well-rounded sand grains in sandstone, along with other mentioned features like shale with plankton fossils, are indicative of sedimentary processes.