Complex sentence: At its greatest extent it covered 400 acres (1.6 km²) in 1853, but was dramatically reduced to 195 acres (789,000 m²) in the 1890s, and subsequently has been reduced to 110 acres (445,000 m²).
Split into simpler sentences: At its greatest extent, in 1853, it covered 400 acres (1.6 km²) but was dramatically reduced to 195 acres (789,000 m²) in the 1890s. Subsequently it has been reduced to 110 acres (445,000 m²).