Capitalizing Proper Adjectives
When an adjective owes its origins to a proper noun, it should probably be capitalized. Thus we write about Christian music, French fries, the English Parliament, the Ming Dynasty, a Faulknerian style, Jeffersonian democracy. Some periods of time have taken on the status of proper adjectives: the Nixon era, a Renaissance/Romantic/Victorian poet (but a contemporary novelist and medieval writer). Directional and seasonal adjectives are not capitalized unless they're part of a title:
We took the northwest route during the spring thaw. We stayed there until the town's annual Fall Festival of Small Appliances.
See the section on Capitalization for further help on this matter.