Haystack Rock the U.S. The tallest and probably best known Haystack Rock due to its proximity to Portland is in Tillamook County located off Pacific City and near Cape Kiwanda. It stands above the sea and is the fourth tallest sea stack or off-shore monolith in the world. Haystack Rock in Cannon Beach is accompanied by several smaller rocks known as The Needles. The other Oregon coastal Haystack Rock stands above sea level in Coos County near Bandon. Composed of basalt, Haystack Rock was formed by lava flows emanating from the Blue Mountains and Columbia basin about 15-16 million years ago. The
West Rock Ridge in faults created by the rifting apart of North America from Eurasia and Africa over a period of 20 million years. Erosion occurring between the eruptions deposited deep layers of sediment between the lava flows and around the dike, which formed sedimentary rocks. The resulting "layer cake" of igneous and sedimentary sheets was later faulted and tilted upward. Subsequent erosion wore away the weaker sedimentary layers a faster rate than the lava layers, leaving the abruptly tilted edges of the lava sheets exposed, creating the distinct linear ridge and dramatic cliff faces visible today along the Metacomet Ridge. West Rock