Science Olympiad Dynamic Planet Practice Test

What is the average density of oceanic crust?

1. 2.5 g/cm³

2. 2.7 g/cm³

3. 2.9 g/cm³

4. 3.1 g/cm³

The correct answer is: 2.9 g/cm³

The average density of oceanic crust is approximately 2.9 g/cm³, making it the correct choice. This density value reflects the composition of oceanic crust, which primarily consists of basaltic rocks rich in iron and magnesium. The density is a crucial factor in understanding the behaviors of tectonic plates and how they interact with the underlying mantle. Oceanic crust is generally denser than continental crust, which averages around 2.7 g/cm³, mainly due to the differences in their rock types and mineral compositions. The higher density of oceanic crust also plays a significant role in plate tectonics, where oceanic plates tend to subduct beneath continental plates at convergent boundaries. In this context, options that suggest densities significantly lower or higher than 2.9 g/cm³ do not align with established geological data regarding oceanic crust. Understanding these densities helps clarify the processes involved in the movement and interaction of tectonic plates, as well as various geological phenomena such as earthquakes and volcanic activity.