MTPR

nurse rocks

Glacial erratic in Yellowstone Park's Lamar Valley
Jo Suderman - National Parks Service

Few sights have the romantic appeal of a lone tree growing in the grasslands of Montana. While these trees are beloved by photographers and artists for the serenity and peace they evoke, their origins typically lie in a more abrasive past. As the Wisconsian and Pinedale glaciations began their slow march from the mountains of western Montana and greater Yellowstone, they picked up rocks of varying sizes from pebbles to house-sized boulders. When the climate shifted and the glaciers melted, the rocks trapped in the ice settled on the ground and became known as glacial erratics.