Answer:
Explanation:
The Dust Bowl of the 1930s was caused by erosion, overgrazing, fertilizer runoff & the clearing of grasslands.
Answer:
great lakes
Explanation:
Water from the melting glacier filled the basins , forming the Great Lakes.
Answer:
b. flat rotation curves in spiral galaxies
Explanation:
Dark matter accounts for majority of the matter in the universe (about 85%). It is considered to be composed of subatomic particles which are yet to be discovered. Dark matter cannot be observed because it does not emit light that can be detected. Only its gravitational effect is visible.
Astronomers when calculated the mass of the visible matter and tried to account for the observed speed of stars in the galaxy, there was a mismatch. To understand what caused this mismatch, astronomers gave name to the invisible matter as the Dark Matter.
The expected velocity of stars should decrease away from the near the center of the galaxy but a constant velocity of stars was observed that is a relatively flat rotation curve was obtained.
Thus, flat rotation curves in spiral galaxies in an evidence of Dark Matter.
Answer:
1-A: A cataract is another term for waterfall
2-E: Ex. European countries colonized North and South America centuries ago
3-F: Escarpment is a word for a steep cliff or slope
4-B: A topographic map shows the geographic features of an area
5-D: A tributary is a smaller stream that always flows into a bigger one
6-C: Veldt is another word for a plateau
