The gravity of the Moon, and to a lesser extent, the gravity of the Sun.
The Moon's gravity is the primary cause of tides - all tides, both high and low.
The earth's rotation and the proximity of the moon (and the sun to a lesser degree) cause high and low tides each day.
High tides, low tides, spring tides (which are maximum high tides) and neap tides (which are the lowest of low tides).
Tides rising and falling
gravitational pull
Fifteen thousand feet.
Because the moon's gravity can cause the tide to go up and down
They consider high and low tides in their journey because if it is high tide the water level will be high but if it is low tides the water level is low.
Low tides
The gravitational pull of the moon causes tides on Earth. This pull creates a bulging effect in the ocean waters, leading to high and low tides as the Earth rotates.
yes
Tides that are not very high and not very low are called neap tides.