Complex sentence: In 1857 heavy spring rains once again flooded Pogue's Run and the White River, although high water marks did not reach the 1847 level, and in 1860 a tornado passed through Indianapolis, but the most significant destruction occurred east and west of the city.
Split into simpler sentences: In 1857 heavy spring rains once again flooded Pogue's Run and the White River, although high water marks did not reach the 1847 level. In 1860 a tornado passed through Indianapolis, but the most significant destruction occurred east and west of the city.