What did scientists of deserve in the ocean floor which indicates that the Pacific Ocean is becoming smaller?
A - plates floating on the mantle
B - continental drift
C - spreading
D - subduction
C - spreading
The correct answer is C - spreading. Scientists have observed evidence on the ocean floor that indicates the Pacific Ocean is becoming smaller due to a process called seafloor spreading. Seafloor spreading is the movement of tectonic plates away from each other, causing the ocean floor to expand and leading to the formation of new oceanic crust. This process occurs primarily along the mid-ocean ridges, where molten rock rises to the surface and creates new crust as it cools and solidifies.
To determine if the Pacific Ocean is becoming smaller, scientists study the ocean floor and look for evidence of specific processes. In this case, the process that indicates the Pacific Ocean is becoming smaller is spreading.
To understand how scientists determine this, we need to start by explaining plate tectonics. The Earth's lithosphere (the rigid outer layer) consists of several large plates, which float on the semi-fluid layer beneath called the mantle. These plates are constantly moving, albeit slowly, due to convection currents in the mantle. This movement is known as continental drift.
At certain areas along plate boundaries, called divergent boundaries, the plates move away from each other. This creates a gap between the plates where new crust is formed through volcanic activity. This process is known as spreading.
In the case of the Pacific Ocean, the boundaries along the eastern and western edges of the ocean are divergent boundaries. This means that the plates on these boundaries are moving away from each other, causing the ocean floor to spread and new crust to be created.
Scientists can obtain evidence of spreading and the growing Pacific Ocean by studying the ocean floor. They use instruments like sonar to map the topography of the ocean floor and identify features called mid-ocean ridges. These ridges are underwater mountain ranges formed by new crust being created at the spreading plate boundaries.
By observing the pattern and age of the oceanic crust on either side of the mid-ocean ridges, scientists can determine that the Pacific Ocean is expanding. The spreading and creation of new crust on the ocean floor provide evidence that the Pacific Ocean is getting larger, rather than smaller.
Therefore, the correct answer to the question is not D - subduction, but rather C - spreading.