Moving Mountains

“Moving mountains” is synonymous with doing the impossible. Yet at least once in the past, one mountain actually picked up and moved a fair distance away. This feat took place around 50 million years ago, in the area of the present-day border between Montana and Wyoming. Heart Mountain was part of a larger mountain range when the 100-km- (62-mile-) long ridge somehow became detached from its position and shifted about 50 km to the southwest. Scientists first realized that the peak was not in its original spot when they discovered that the rock formation underneath was younger than the mountain sitting on top of it. Later satellite images helped them to place the original position of the mountain. This “migrating mountain” has garnered interest from geologists and geophysicists around the world, who have tried to solve the mystery behind the largest known instance of land movement on the face of any continent. Dr. Einat Aharonov of the Weizmann Institute’s Environmental Sciences and Energy Research Department, working in collaboration with Dr. Mark Anders of Columbia University in New York, published a paper in the scientific journal Geology that offers an explanation for the phenomenon.

 

In the scenario put forward by Aharonov and Anders, the mountain range was permeated with vertical cracks in the rock, called dikes, filled with hot lava boiling up from deep in the earth. This particular range had a relatively large number of these dikes, creating conduits in the rock leading from the lava source many thousands of meters below the surface upward to a 3-kilometer-deep aquifer – a porous, water-soaked layer of limestone. There, the sizzling lava would have heated the water to extreme temperatures, causing the pressure in the trapped fluid to rise tremendously. The scientists developed a mathematical model (based on the number of dikes in the mountain and their structure) that enabled them to calculate the temperatures and pressures that would have been created deep within the base of the mountain. The results showed that the hot lava would have turned the water in the aquifer layer into a sort of giant pressure cooker, releasing enough force to literally move a mountain.