When first mapped in the early nineteenth century, the island was estimated to cover approximately 100 acres (40 ha) and consisted primarily of marshland.[1][8] The island's size increased to 138 acres (56 ha) due to soil and rock deposits from the excavation of the Erie Canal in 1819, and further grew in 1908 with the addition of material generated from the construction of a canal lock in Black Rock.[7] The island was estimated to be 200 acres (81 ha) in 1912,[3] but was reduced to just 40 acres (16 ha) by 1948 due to unregulated gravel mining operations during the early and mid 1900s.[3][4] The island was further diminished to 25 acres (10 ha) by 1950 as dredging was concentrated on the island's center, expanding its lagoon.[7] The island continued to lose area due to erosion from high water levels and winter storms during the latter half of the 20th century.