The correct answer is (B) They are both Northern Hemisphere, warm-temperate forests. Although Appalachian (U.S.A.) and Southwestern Caucasus (Russia) have common origins, both northern hemisphere warm-temperature Tertiary forests, they have developed differently. The similarities also include the species-to-genus, species-to-families ratios and the floristic composition.
Answer: Gravity made the dust and gas in the nebula collide, flattening these materials into a disk.
Explanation: The nebula theory is a scientific explanation of how the planets and our solar system were formed. It suggests that our solar system was formed more than 4 billion years ago due to the effect of gravity on a cloud of gas and dust which were flattened into a disk. The gravity was so great that the matter in the nebula were made to collide against each other until they were compacted to form our sun.
The source of soil is called parent material.
