Ever wondered how the world came to know about the existence of dinosaurs? Or the other amazing creatures that last walked the earth millions of years ago? Well, fossils are the key to unlocking this mystery. NCERT Solutions For Class 10 Science tells us that fossils are not really bones but in fact rocks. Let us understand what are fossils? and how they formed.
How are fossils formed?
When an animal dies in an environment that has moving sediment, like a river or an ocean, its soft parts like flesh decompose until only the bones remain. The bones also have organic components like RBC and collagen which break down over the course of time, leaving only inorganic materials like calcium. The bones become porous, and these pores are eventually filled by other minerals in the sediment, literally turning it into stone. The process of fossilization is comparable to a sponge that has soaked up a lot of glue. I.e., the physical structure remains the same.
Of course, bones are not the only things that can be fossilized. Footprints, especially the ones made near a river bank will fill with sediments and eventually harden, turning it into a cast. Similarly, animal dung (also called coprolites), teeth, tunnels and animal burrows also fossilize, giving us an insight into the animal and its behavior.
How are fossils dated?
The date of fossils and their surrounding sediments are very hard to determine directly. Instead, there are two alternatives to find out the date of the fossils namely Absolute dating and Relative dating.
Absolute dating
In absolute dating methods, the exact age of the fossils is found through various tools like carbon dating, radiometric dating. Here, the half-life of an element that is trapped in the fossil is used to arrive upon the exact age or the age range of the fossil.
Relative dating
Relative dating measures the age of the fossil in relation to another fossil or site. In other words, the exact age of the fossils cannot be determined, but rather, which of the two artifacts predates the other. This technique employs stratigraphy, where the layers of rock and their positioning are studied. This gives an insight into the geographical timescale and inferences from these are used to estimate an age range for a fossil. In conclusion, this was everything you need to know about fossils.
You can find the most comprehensive and detailed answers for all your exam questions through NCERT Solutions, These topics and concepts are explained in a simple language aimed for easy understanding. From fossils to Faraday’s Laws, discover everything you need to know for your upcoming exams.
