iridium
The term 'tombstone layer' is a colloquialism associated with an extinction event ~ 66 million years ago leading to the demise of the dinosaurs and about 70% of other life on earth. The layer is a thin (few inches) clay deposit containing iridium (a very rare element) at a level about 100 times its normal distribution in the earths crust. The layer has been positively linked to the Chicxulub impact crater discovered in the Yucatan Penisula, Mexico and credited with being the extinction event that ended in the mass extinction, thus the term 'tombstone layer'.
The element which is found in the four layers of earth is hydrogen. There is a percentage of hydrogen in every layer of the earth.
The thinnest layer of the Earth's crust can be found underwater.
The thinnest layer of the Earth's crust can be found underwater.
The layer with soil is the lower mantle
rtr
the crust
Ground
The ozone layer is not found on the earth. Rather it is founded in the atmospheric layers.
Crust, Mantle, Inner Layer, Outer Layer
The ozone layer is found in the stratosphere region of the atmosphere. It protects us from the UV radiations of the sun.
See "Where is the ozone layer found?" in the "Related questions" section below.