Layers of carbonate limestones, silty mudstones, quartz sand and solidified lava show that within the past 600 million years, this area was a warm, shallow sea, then a muddy swamp, then a vast desert of shimmering hot dunes, then a glacial ice sheet, then
Layers of carbonate limestones, silty mudstones, quartz sand and solidified lava show that within the past 600 million years, this area was a warm, shallow sea, then a muddy swamp, then a vast desert of shimmering hot dunes, then a glacial ice sheet, then
层层的碳酸石灰岩、粉砂质泥岩、石英砂和凝固的熔岩，显示在过去六亿年间，这个区域曾经是温暖的浅海，接著依序变成泥泞的沼泽、拥有炙热沙丘的广阔沙漠，然后是冰川，后来又再度成为浅海。