Mt. Rushmore (image) University of Missouri-Columbia Share Print E-Mail Caption Mt. Rushmore granite crystallized from a magma that was generated 1.7 billion years ago during collision of smaller tectonic plates that together produced the nucleus of the North American continent. Reduced heat diffusion in colliding and deforming tectonic plates, as reported in the paper, contributed to melting of crustal rocks in the ancient mountain belt, in a manner analogous to granite production in the active Himalayan continental collision. Credit Photo courtesy of Peter Nabelek. Usage Restrictions None Share Print E-Mail Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.