Again in this case, the situation is different for swimming, creeping or quadrupedal (prone) animals than for Man, or other erect species, due to the changed position of the axis.
A mid-sagittal plane divides the body and brain into left and right halves; sagittal sections in general are parallel to this median plane, moving along the medial-lateral dimension(see the image above).
The continental crust is typically from 30 km (20 mi) to 50 km (30 mi) thick and is mostly composed of slightly less dense rocks than those of the oceanic crust.
Some of these less dense rocks, such as granite, are common in the continental crust but rare to absent in the oceanic crust.
The crust occupies less than 1% of Earth's volume. The oceanic crust of the sheet is different from its continental crust.
The oceanic crust is 5 km (3 mi) to 10 km (6 mi) thick and is composed primarily of basalt, diabase, and gabbro.
Estimates of average thickness fall in the range from about 50 to 60 km.
Most of this plagioclase-rich crust formed shortly after formation of the moon, between about 4.5 and 4.3 billion years ago.
Earth has probably always had some form of basaltic crust, but the age of the oldest oceanic crust today is only about 200 million years.
In contrast, the bulk of the continental crust is much older.
Partly by analogy to what is known about the Moon, Earth is considered to have differentiated from an aggregate of planetesimals into its core, mantle and crust within about 100 million years of the formation of the planet, 4.6 billion years ago.
The primordial crust was very thin and was probably recycled by much more vigorous plate tectonics and destroyed by significant asteroid impacts, which were much more common in the early stages of the solar system.
The crust of the Earth is composed of a great variety of igneous, metamorphic, and sedimentary rocks. The upper part of the mantle is composed mostly of peridotite, a rock denser than rocks common in the overlying crust.