Which characteristic is shared by extrusions, intrusions, and faults?

Intrusions, extrusions of igneous rocks, and faults and gaps all share a common feature, that is, they help geologists and scientists in determining the relative age of rocks.  

Igneous rock is produced when the lava or magma hardens. The lava, which toughens on the surface is known as extrusion. The layers of the rock below an extrusion are always older in comparison to the extrusion. Within the surface, magma may push within the bodies of rock. There, the magma cools and hardens into a mass of igneous rock known as an intrusion.  

An intrusion is always younger in comparison to the layers of rock around and beneath it. Even more, clues come from the examination of faults. A fault refers to a break in the crust of the Earth. A fault is always younger in comparison to the rock it cuts through.  

an individual’s sex (i.e., whether they are a male or female) is determined by the sex chromosomes. most people have two sex chromosomes, one that is inherited from their mother and one that is inherited from their father. typically, females have two x chromosomes (xx) and males have one x chromosome and one y chromosome (xy). conditions caused by changes (“mutations”) in genes located on the x chromosome are considered x-linked.

x-linked recessive inheritance

most x-linked conditions are recessive. this means that in a person with two x chromosomes (most females), both copies of a gene (i.e., one on each x chromosome) must have a change or mutation whereas in a person with one x chromosome (most males), only one copy of a gene must have a mutation. a female with a mutation in one copy of a gene on the x chromosome is said to be a “carrier” for an x-linked condition. a male with a mutation in a gene on the x chromosome is typically affected with the condition. because females have two copies of the x chromosome and males have only one x chromosome, x-linked recessive diseases are more common among males than females. however, x-linked recessive diseases can occur in both males and females.

for x-linked recessive disorders, an unaffected carrier mother who has a mutation in a gene on the x chromosome can transmit either the x chromosome with this mutation or a “normal” x chromosome to her children. if the father is unaffected, none of her daughters will be affected and all of her daughters will be unaffected—since they will inherit at least one normal x chromosome from their father. however, each daughter will have a 50% chance of being an unaffected carrier like her mother and a 50% chance of both x chromosomes being normal.