In the early 1950s, cartographer Marie Tharp systematically analyzed thousands of bathymetric echo-sounding profiles collected by geologist Bruce Heezen across the North Atlantic seafloor. While plotting the depth measurements, Tharp identified a consistent V-shaped depression running continuously along the crest of the Mid-Atlantic Ridge. She hypothesized that this central notch was a rift valley—a structure created by the tension of oceanic crust pulling apart. Initially, Heezen dismissed her interpretation as an artifact of measurement error, attributing the bathymetric anomalies to localized surface faulting rather than a continuous tectonic boundary.
To test her hypothesis, Tharp sought independent confirmation by cross-referencing her topographic maps with seismic data compiled by colleague Howard Foster. Foster had plotted the precise geographic epicenters of mid-oceanic earthquakes recorded throughout the Atlantic basin. Tharp discovered that these earthquake epicenters aligned almost perfectly with the central axis of her proposed rift valley, rather than dispersing randomly across the abyssal plains. This spatial correlation indicated that active faulting and seismic displacement were concentrated directly within the central notch.
When Heezen presented this overlay of seismic epicenters and topographic profiles at a scientific symposium in 1956, the spatial coincidence convinced many sceptics of the rift valley's physical reality. Nevertheless, widespread acceptance of Tharp's findings within the geological establishment remained slow, largely because the prevailing geophysical paradigm still favored static continental basins over models of dynamic crustal motion.
According to the passage, Marie Tharp took which of the following actions to corroborate her hypothesis regarding the central notch along the Mid-Atlantic Ridge?
- She compared her topographic bathymetric maps with plotted locations of oceanic earthquake epicenters.Cevap
- BShe re-calibrated the echo-sounding instruments to eliminate data distortions caused by surface faulting.
- CShe plotted an independent series of bathymetric soundings across the abyssal plains of the South Atlantic.
- DShe demonstrated that seismic hypocenters were distributed uniformly throughout the ocean floor.
- EShe published a theoretical paper establishing that continental landmasses expand dynamically over time.