The turn timer for Civilization 4 multiplayer has a number of options that are defined by descriptive words, such as "Slow", "Blazing!!!", or "Snail." These names are necessary since the amount of time that is given for turns on any setting is dynamic depending on the era of the game - the length gets longer as the game progresses.
What is the formula for this amount of time? How long does each setting give you on any given turn, and how is it calculated? Additionally, if quick combat is disabled, time is added during each combat - where is this amount controlled?