Complex sentence: One, modern rock nationwide reached it's peak in popularity during the period when The Rocket was an alternative rock station, and two, the Lafayette market did not have a Top 40 station in the market at the time.
Split into simpler sentences: One, modern rock nationwide reached its peak in popularity during the period when The Rocket was an alternative rock station. Two, the Lafayette market did not have a Top 40 station in the market at the time.