I want to know the answer to the following question:
Along with Devonian slate, Middle Devonian limestone and limestone, what stone provides the geologic base of Plymouth?
All the background I'm provided with is that "The bulk of the city is built upon Upper Devonian slates and shales and the headlands at the entrance to Plymouth Sound are formed of Lower Devonian slates, which can withstand the power of the sea.". Is that enough to answer the question?
Answer: no