The atlantic ocean and the great lakes have different elevations. which two human made structures ships navigate through the sea way?

Locks and Canals

Explanation:

The Atlantic Ocean and the Great lakes have different elevations because of canals and locks that help in bringing ships to navigate through the seaway. The canal is human-made waterways that permit ships from both sides to enter and reduces the time of journey. The locks in canals help in altering the level of water of the canal by filling it up or decreasing it.

a mid-ocean ridge or mid-oceanic ridge is an underwater mountain range, formed by plate tectonics. this uplifting of the ocean floor occurs when convection currents rise in the mantle beneath the oceanic crust and create magma where two tectonic plates meet at a divergent boundary.a geomagnetic reversal is a change in a planet's magnetic field such that the positions of magnetic north and magnetic south are interchanged.

a. themes: sub fields