Highwall mining is often used when excavating an open-pit mine becomes too expensive. There are many advantages over underground mining, including the fact that it is both more cost-effective and involves less lead time.
Saltation - During wind erosion, wind carries loose material from the bed, but transports it back to the surface later. This can be done by any fluid, like water too. Other examples of saltation include transport of pebbles by river and snow drifting over smooth surfaces in the Arctic.
Answer:
Donald Trump
Explanation:
Bout to be Biden though. Election 2020!
Different regions have different available resources. The need for certain resources is sometimes greater than resource availability in a given area. This leads the necessity to acquire needed resources from another area. Countries can export or import resources based on need, but there is algo the concern of finances as well.
Answer:
a) Yes! the American chestnut tree is a native species. The American chestnut tree was present before the Europeans arrived in North America in the 1600s. Since a native species has been defined as any species that was present in North America before the arrival of the Europeans, then it is a fact that the North American chestnut tree is a native species.
b) The chestnut blight is an invasive species that is native to east East Asia, and was accidentally introduced into North America around the early 1900s, when the Japanese chestnut was commercially cultivated in the United States.
c) Invasive species tend to proliferate at a very high rate because they lack some natural constraints in the new environment such as natural predators, competition, and as in the case of this chestnut blight; the host has no natural defense mechanism against them. These conditions allow them thrive more than they would in their natural environment, unchecked
d) Yes, I agree with this idea, albeit to some extent. The development of hybrid chestnut resistant to the chestnut blight will possibly return the forests back to how it was before the Europeans arrived in the 1600s, but the genetic conservation will be altered, since these new trees will be an hybrid of the old trees, and the forest won't truly be as it was before the 1600s
