How are young volcanoes evidence of cracks in
the earth's surface to magma below?

These separating borders create fractures and fissures in the rocks. It is these cracks in the land that allow hot magma to surge upwards and fill the gaps.

when you breathe in, or inhale, your diaphragm contracts (tightens) and moves downward. this increases the space in your chest cavity, into which your lungs expand. the intercostal muscles between your ribs also enlarge the chest cavity. they contract to pull your rib cage both upward and outward when you inhale.