Most stream valleys have a V shaped cross section because . A. water washing down the slope makes straight channels. B. vegetation on the slopes forces this profile. C. mass wasting of weathered rocks on the slope maintain an angle of repose slope. D. None of these

The most direct route from south america to asia is across the ocean.

Which evidence is most likely used to indicate the beginning of solar system formation? a. materials combined to form a mass. b. materials were pulled together by gravity. c. water condensed and collected to form oceans. d. different species of microorganisms lived on earth.

These factors threaten north americas ecosystems