It is overlain by the Dawson Arkose. This suite consists of metamorphosed siltstone, wacke, conglomerate, arkose, and minor rhyolite. This locale is part of the New Haven Arkose, a substrata of the Newark supergroup. Quartz-only sands are more mature than arkose or greywacke. Jotnian sediments consist of quartz-rich sandstone, arkose and conglomerate. Metamorphic rocks of slate, schist and arkose dominate the northern part of the island. Jotnian sediments include quartz-rich sandstones, siltstones, arkose, shale and conglomerates. Minor basalt flows occur within the Arkose Ridge Formation. These sediments are typically quartz-rich sandstones, siltstones, arkose, shale and conglomerates. Its cliffs, made of arkose sandstone, are a very prominent landscape feature visible for miles. Roughly 200 million years ago, the New Haven Arkose began to be deposited. The Arapahoe Formation and the Dawson Arkose are also included in the D1 Sequence. Several thousand feet of salt accumulated beneath arkose shed off the mountains. The resulting Cutler red beds are made of iron-rich arkose sandstone. The bottom layer is composed of "arkose sandstone," visible on Mount Sugarloaf.