No one really knows how the High Plains got so high. Å·ÃÀ¿Ú±¬ÊÓƵ 70 million years ago, eastern Å·ÃÀ¿Ú±¬ÊÓƵ, southeastern Wyoming, western Kansas and western Nebraska were near sea level. Since then, the region has risen about 2 kilometers, leading to some head scratching at geology conferences.