What are Hoodoos? Hoodoos or Goblins are one of the most spectacular displays of erosion. They are geological formations, rocks protruding upwards from the bedrock like some mythical beings, conveying the story of hundreds and thousands of years of weather erosion. Most Hoodoos are made of sandstone, sand-sized particles cemented together by calcite, silica, or iron oxide. They are created by erosion. Rains, running water and strong sand winds slowly chip away the material from the bedrock. As some parts of the sandstone are stronger than others, uneven shapes of remains begin forming.