Question

Sandstone strata and a mass of granite are observed to be in contact. Which of the following statements is correct geologically?

a.The sandstone is younger if the granite contains sandstone inclusions.

b.The granite is older if the sandstone contains pebbles of the granite.

c.The granite is older if it contains inclusions of sandstone.

d.The sandstone is younger if it shows evidence of contact metamorphism.

Answer 1

Option B and D are correct

The granite is older if the sandstone contains pebbles of the granite.

The sandstone is younger if it shows evidence of contact metamorphism

Step-by-step explanation:

In rock dating, the presence of rock inclusions suggest that the interior rock is of an older origin.

For example, if lava flows from a volcano and carries rocks in its paths, the rocks that are carried will form inclusions in the newly formed rocks once the magma cools.This is because the new rock will simply wrap round the older rock.

Similarly, contact metamorphism refers to metamorphism due to contact with or proximity to an igneous intrusion. If the sandstone shows evidence of contact metamorphism, it is younger than the granite rocks.

Answer 2

Answer: The statement that is correct geologically is

b) The granite is older if the sandstone contains pebbles of the granite

Step-by-step explanation:

Sandstone is a sedimentary rock that contains sand-size grains which are bonded either by a cohesive rock or chemical cement. The granite is a igneous rock with a grain size that is big enough to see, the granite contains a vast amount of feldspar and quartz.

It is said from the question that, sandstone strata and a mass of granite are observed to be in contact, since the sandstone strata is in contact with just a mass of granite and pebbles(small amount) of granite is still present in the sandstone, geologically, it can be said that the granite is older than the sandstone strata considering the sizes of grain of both rocks