The City of Rocks State Park in New Mexico was formed approximately 34 million years ago by a volcanic eruption. Over the years the rocks have been smoothed by weather to create spires and pinnacles which resemble a city. The rocks cover one square mile in the Chihuahuan desert at 5200 feet elevation halfway between Deming and Silver City. This is truly a cool place to see, the rocks just pop up out of nowhere in the middle of the desert.