Chapter 10.1, Problem 1BYL

To determine

The four methods used to explore the topography and rocks of the seafloor.

Answer to Problem 1BYL

The mapping of the ocean floor needs remote observation of the ocean bottom with the help of the sound waves bouncing off the ocean floor and by some other methods. The rock samples present on or underneath the ocean floor are being collected by the geologists and oceanographers by traveling down into the ocean in small submarines (submersibles) or using ships for drilling holes through the rock and sediment. Important information on the ocean floor may also be obtained from the satellites moving in the Earth’s orbit.

Explanation of Solution

The exploration of seafloor is tougher than the exploration of land. The mapping of some portions of the ocean floor can be done by sending sound waves from a ship into the ocean, which reflects back to the sensors fixed on the ship after touching the ocean bottom. The time taken by the sound waves to travel from the ship and return back to the sensors is taken to calculate the depth of the ocean floor. This is referred to the sonar technique.

The use of submersibles, which are small submarines that can carry two or three individuals, is another way to study the ocean floor. The direct observation of the geologic features and processes occurring at the ocean floor becomes possible in case of submersibles. Photographs can be taken, and the samples of seawater, rocks, and life forms can be collected by the scientists from the submersibles. Smaller robotic varieties of submersibles can be operated from the ship itself.

With the help of specially equipped research vessels, the geologists are able to drill exploration holes into the ocean floor. The samples of volcanic and sedimentary rocks that compose the upper portion of the ocean crust could be recovered by the scientists. The layers retained in the drill cores facilitate the geologists to reconstruct the series of past events, the age of the rocks, and the changes in the sea water chemistry with time.

The satellites orbiting around the Earth can give significant data on the oceans. Most of the satellites observe the ocean floor found beneath very shallow water. They are basically used in surface measurements such as the surface-water temperature or the sea surface height.