Author’s Note: This part of a weekly series on geology for a class I am taking this semester at BYU-Idaho. This week’s prompt required students to look at the anatomy of a mid-ocean ridge. Other posts from this assignment can be found under the “Geology 111” category.
Throughout the summer, the Atlantic Ocean is on the back of the minds of many meteorologists as the hurricane season gets underway. Last year’s hurricane season was a fascinating one, with cataclysmic storms like Hurricane Harvey striking the United States and Caribbean. While folks like me are fixated on the atmosphere above the Atlantic, a slowly spreading rift continues to grow thousands of feet below the surface.
The Mid-Atlantic Ridge is the boundary between the North and South American Plates and their counterparts in the Old World. Spreading at 2cm a year, this ridge continues to slowly widen the Atlantic Ocean.
At the center of the ridge is a rift valley which is as deep as the Grand Canyon. Radiating out from this valley is a rough series of mountains which decrease in elevation the farther they get from the center. The higher elevation near the center is due to the warmer temperatures of the rock there. Since the rate of material ejection is relatively slow (some spreading centers exceed 10cm/year), the rift valley is deep and extremely visible on maps and elevation profiles.
Having just been ejected from deep below the ocean floor, this rock is warmer and therefore more buoyant atop the mantle. After millions of years of cooling, the elevation of the rock sinks by several thousand feet.
While much of the ridge lies below sea level, parts of it (like Iceland) reach high enough to break through the water’s surface. Mid ocean ridges account for approximately 60% of the volcanic material ejected by the Earth.
