The land that is Orange County was part of the first land to come up from below the Early Oligocene sea 33.9–28.4 million years ago and is known as Orange Island. Orange County's Rock Spring location is a Pleistocene fossil-bearing area and has yielded a vast variety of birds and mammals including giant sloth, mammoth, camel, and the dire wolf dating around 1.1 million years ago.Petuch, Edward J., Roberts, Charles; The geology of the Everglades and adjacent areas, 2007, .
The land that is Orange County was part of the first land to come up from below the Early Oligocene sea 33.9–28.4 million years ago and is known as Orange Island. Orange County's Rock Spring location is a Pleistocene fossil-bearing area and has yielded a vast variety of birds and mammals including g.iant sloth, mammoth, camel, and the dire wolf dating around 1.1 million years ago.Petuch, Edward J., Roberts, Charles; The geology of the Everglades and adjacent areas, 2007, 