How are oceans and rivers barriers to human trade, movement, and migration?

check all that apply.

a. they are a natural boundary.
b. they divide landmasses.
c. they can be hard to cross or navigate.
d. they might be hard to get to like the amazon.

Computer models can scientists predict weather. some computer models can show the predicted path of hurricanes. what other events could a computer model warn us of? a) undersea earthquakes , tornadoes, and avalanches b) tornadoes c) avalanches d) undersea earthquakes

What is the general rule about surface currents? cold water flows along the ocean floor towards the equator. the east coasts of continents have cold surface currents, and the west coasts of continents have warm surface currents. seasonal and constant offshore winds create significant upwelling along the west coasts of south and north america and africa. the west coasts of continents have cold surface currents, and the east coasts of continents have warm surface currents.

What is the approximate chemical composition of the solar nebula?