Sandstone is formed from tiny particles of sand cemented together. Sandstone is a <u>a sedimentary rock</u> .
For example, when a government imposes an import tariff, it adds to the cost of importing the specified goods or services The additional marginal cost added by the tariff discourages imports, thus affecting the balance of trade.
The correct answer is - biomass from the decomposing grasses.
The Midwest is a region known for its highly fertile soil. The reason for this is that the weathered bedrock combines with huge amounts of biomass. The biomass is almost entirely form the grasses. The grasses grow naturally in this region and they dominate the landscape. They grow and die out relatively quickly, as most of those grasses are one season grasses. They manage to create very large amounts of biomass every year, and also they decompose very quickly. The grasses also are high in nutrients, so once decomposed, they give the soil a lot of nutrients as well, which makes it very fertile and suitable for agriculture.
