Complex sentence: Rock quarries developed here in the late 19th century due to the combination of an abundant supply of quality stone, and convenient transportation on the canal; businesses selling stone products continue in the Sag Bridge area today.
Split into simpler sentences: Rock quarries developed here in the late 19th century due to the combination of an abundant supply of quality stone, and convenient transportation on the canal. Though the quarries themselves no longer operate, businesses selling stone products continue in the Sag Bridge area today.