Which of the following describes how Marie Tharp and Bruce Heezen found evidence that led to the theory of plate tectonics? (1 point)
Marie Tharp and Bruce Heezen found evidence that led to the theory of plate tectonics through mapping the ocean floor and identifying the presence of a large underwater mountain range called the Mid-Atlantic Ridge, as well as the existence of deep ocean trenches.
answers: b
a,c
c
b
The correct answer is: a,c
Marie Tharp and Bruce Heezen contributed significantly to the development of the theory of plate tectonics through their mapping and analysis of the seafloor. To find evidence supporting this theory, they conducted research and made several key observations.
First, they used sonar technology to create detailed maps of the ocean floor, revealing the presence of vast underwater mountain ranges known as mid-ocean ridges. These ridges showed up as long, continuous chains of underwater volcanic activity.
Next, Tharp and Heezen noticed that the mid-ocean ridges were not uniformly distributed. Instead, they observed variations in the height and shape of the ridges, as well as rift valleys running along their centers.
By examining these variations, they discovered a pattern: the magnetic properties of the rocks on the ocean floor were symmetrically arranged around the ridges. This led them to the concept of seafloor spreading: the idea that new oceanic crust forms at the ridges and spreads outwards on either side.
Tharp and Heezen also collected sediment samples from the seafloor and found that the age of the rocks increased with distance from the ridges. This correlation indicated that the seafloor was getting progressively older with distance, which was consistent with the idea of seafloor spreading.
These observations and findings provided strong evidence supporting the theory of plate tectonics. Tharp and Heezen's work helped to establish the concept that the Earth's lithosphere is made up of a series of tectonic plates that move and interact with each other, leading to various geological phenomena such as earthquakes, volcanic activity, and the formation of mountain ranges.