Plate Tectonics and Continental Drift: A Young Science

Plate tectonics and continental drift is a relatively young science. This story begins only 70 years ago. These sciences are relatively young, and it took decades for them to become approved theories. We still have much to learn about them, but here is the short story.

The Groundbreaking Discovery of Mid-Ocean Ridges

Marie Tharp and Bruce Heezen: Revolutionizing Oceanography

In the 1950s-60s, Marie Tharp and Bruce Heezen revolutionized our understanding of oceanography by discovering the Mid-ocean ridges and rift zones. Their research drastically improved our understanding of the Earth's structure and composition.

Marie Tharp: Mapping the Ocean Floor

Tharp, an American geologist and mathematician, is credited with mapping the Mid-ocean ridges. Combining bathymetric data with seismic data provided by Bruce Heezen and early oceanic research vessel expeditions, she created the first comprehensive map of the underwater mountain ranges that stretch around the world and are found in all five oceans.

The Challenges of 1950s Science

In the 1950s, science was undergoing many new and difficult transitions. Without modern computing, everything was done by hand. Tharp worked tirelessly with sheer ingenuity and determination to interpret the data. Plotting the peaks, plains, and troughs was done carefully using slope changes and raw "fathometer records" to reveal what had never been seen before.

Burning the midnight oil, the complexity of the ocean floor finally became apparent. What once were just dots and plots on a graph revealed abyssal plains and continental rises. This new knowledge presented a major problem, as the term "continental drift" was considered heretical by most scientists at the time.

The Scientific Struggle: Continental Drift Becomes Reality

Tharp and Heezen entered a period of tension and anxiety, as their findings suggested that continental drift was not pseudoscience but an accurate theory. The moment was akin to what Charles Darwin experienced when his theory of evolution became the only logical conclusion.

"If there was such a thing as continental drift, it seemed logical that something like a Mid-ocean rift valley might be involved. The valley would form where new material came up from deep inside the Earth, splitting the Mid-ocean ridge in two and pushing the sides apart. That, in turn, would move the continents on their various tectonic plates," - Marie Tharp

The Mid-Ocean Ridges: Earth's Tectonic Engine

The discovery of Mid-ocean ridges and rift zones provided valuable insight into the Earth's crust. The process of seafloor spreading along these ridges allowed for the continuous formation of new oceanic crust. Ridges or rift zones form when two tectonic plates begin to separate. Tharp and Heezen's work revealed that molten magma was being forced through these plates, splitting them apart. When the magma cooled, it created a new crust along the rift zone.

A Fundamental Shift in Earth Science

Tharp and Heezen's work fundamentally changed the way we view the Earth and geological processes. Like the seams on a baseball, we now know that the Mid-Ocean ridge system wraps around our planet, stretching some 40,000 miles. These ridges form at divergent plate boundaries, where tectonic plates spread apart and produce new oceanic crust. This movement allows molten rock to rise to the surface, leading to massive volcanic eruptions of basalt.

The rate at which plates move affects the ridge's shape. A slower spread results in uneven and steep terrain, while a faster spread creates a wider, more gently sloping landscape.

Exploring the Mid-Ocean Ridge System

The Mid-Atlantic Ridge

The Mid-Atlantic Ridge is located in the middle of the Atlantic Ocean and is gradually widening at a pace of 2 to 5 centimeters (0.8 to 2 inches) per year. This process creates a rift valley similar in depth and width to the Grand Canyon.

The East Pacific Rise

The East Pacific Rise is spreading faster than the Mid-Atlantic Ridge, at rates of 6 to 16 centimeters (3 to 6 inches) per year. Despite being one of the most significant geological features on Earth, much of the mid-ocean ridge system remains unexplored.

Dive Deeper: The Lost City Hydrothermal Vent System

Photo courtesy: by IFE, URI-IAO, UW, Lost City Science Party; NOAA/OAR/OER; The Lost City 2005 Expedition. - NOAA Photo Library: expl2286

Picture information: Basaltic rocks of the Lost City Expedition observed at the Mid-Atlantic Ridge by the Hercules ROV.

Look up the Lost City hydrothermal vent system in the Atlantic Ocean to dive deeper! This incredible geological wonder will be our topic in the next blog!

Conclusion: A Timeline of Scientific Progress

These blogs help serve as a timeline, showing how far science has come in such a short time!