The simple fact that Montague is a massive island located near the East Australian Current gives it an incredibly unique environment. With it only being located 5 nautical miles from the continental shelf, its environment is heavily impacted by its size and precise location.
Montague Island resembles a large rectangle, with its widest point measuring 1.4km long and 525 meters wide. A large gully divides the northern and southern sections of the island and covers over 30% of the island’s total area. The ravine is so large that, although Montague is a single island, it is often referred to as being comprised of both north and south “islands”.
The color contrast on the island provides for a breathtaking landscape. The south section of the island is covered in grey and brown rocks, while the north section is littered with dark black rocks. A layer of neon orange lichen is sprinkled over the tops of the rocks, which makes for quite a sight when the waves crash against them. The bright white lighstation can be seen clearly, overlooking the island, due to the low vegetation.
The island’s geology is quite fascinating. It comprises part of the Cretaceous Mount Dromedary Igneous Complex. On the southern end of the island, a granitic rock, banatite, can be found while the northern end of the island is home to andesitic lava. The rock outcrops on the southern end of the island stretch high into the air, 64 metres above sea level. On the northern side, there aren’t nearly as many rock outcrops and none of which that are particularly high. However, the coastline on the northern side of the island is littered with steep cliffs. Several small bays exist on the island, although their “beaches” are only several metres wide during low tide. 1m thick sand dunes cover most of the island and the slopes of these sand dunes contain swamps. The presence of these remnant sand dunes remind visitors of the island’s unique history. The island’s coastline was formed over 8500 years ago when it was cut off from the mainland.
The flora on the island has changed over time. Photographs taken years ago serve as evidence that the southern side of the island used to be filled with greenery like small trees and shrubs like acacias and casuarinas. Today, there is no evidence of this native flora. It is assumed that the lack of trees is a result of lightkeepers obtaining firewood and that grazing animals have destroyed the shrubs. However, over the years, over 160 plant species have been recorded on the island. 50% of these species were introduced to the island, either by nature of humans, while some of the original native plant species imply the island’s original ties to the mainland.
Matrush, also known as Lomandra longifolia, is the most common vegetation on the island. It coats the ground on the majority of the island. Along with matrush, bracken, tussock grass and blady grass can also be found throughout most of the island.
Each of these types of vegetation are dominant in their own local territories on the island. For example, Tussock grass dominates much of the northern island slopes. Some shrubs such as Westringia fruticosa, Pelargonium australe, Melaleuca armillaris and Correa alba can be found on the edges of cliffs and in areas secluded from grazing animals. Additionally, the only Acacia species on the island, Coastla Wattle, can be seen scattered around the island in small groupings. Reed and ferns grow in the swampy areas of the island, while ferns can also be found below cliffs. There are several ground covers and herbs that grow on the island, as well.