Why barriers have been affective against erosion?​

Which revelation resulted from the observation of the spectrum of different galaxies? a. there were more galaxies whose spectrum was blueshifted b. there were no galaxies whose spectrum was redshifted c. there were more galaxies whose spectrum was redshifted d. there were no galaxies whose spectrum was blueshifted

Uncle tom's cabin started out as a series of articles printed in the national era, a newspaper.

What causes the drought cycles in africa? a. the jet stream b. mount kilimanjaro c. monsoon climate zones d. quickly evaporating rainwater