The theory of plate tectonics added new information about plates vs. continents to the original theory of continental drift. explain the difference.

Continental drift is a theory first presented by Abraham Ortelius (Abraham Ortels) in 1596. The concept was independently developed by German geologist Alfred Wegener in 1912. The theory states that the continents are moving slowly on the surface of the earth, and the majority of these large landmasses were together once, about 200 million years ago. This collection of continents is known as a super continent while Plate tectonics is the theory explaining the motion of the outer crust or the lithosphere of earth. Lithosphere is divided into tectonics plates. Two main types of tectonics plates are the oceanic crust and continental crust. Oceanic crust is mainly composed of Silicon and magnesium, hence called SIMA. Continental crust is made of Silicon and Aluminum and called SIAL. Each crust type is about 100km thick, but continental crust tends to be thicker. Below the crust lies the asthenosphere.

an effect of the steamboat's popularity was that people began building canals in the united states and europe. this was done to find another way to transport goods across the country and in that time, transportation using the river was very slow and dangerous. it depended entirely on manpower and the current of the river. that all changed in the late 1700's when steamboats were introduced. they soon revolutionized travel and trade through the river and dominated the waterways. eventually, other means of transportation took over from the steamboats, but there was a time that they the united states to expand to the west.

a. the astrolabe could determine the correct latitudinal location of the ship