Answer:
C. A mass of air that is similar in temperature and humidity
Explanation:
An "air mass" refers to a big volume of air that is characterized by having similar or uniform "temperature" and "humidity"<em> (moisture).</em> They come from different source regions, thus they are classified accordingly.
The<em> "cold air masses"</em> come from the <u>polar area</u>s while the<em> "warm air masses"</em> come from the<u> tropical areas.</u> An air mass may cause a storm, for example, when an air mass moves to a new region and confronts another air mass there with a<em> different humidity and temperature</em>.
The correct option is LOESS.
Loess refers to a compacted yellowish deposit of wind blown sediments which is usually found extensively in the mid latitudes. Loess is formed by the accumulation of dust that had been blown by the wind. Scientists believed that about 10% of the earth's land area is covered by loess.<span />
What does the question say?
Answer:
http://liberalsenateforum.ca/issue/canada-in-the-world/
<span>The rock layers must have formed at different times because they contain two different biozones.
The rock layer containing the trilobites must have formed before the one containing the ammonites.
The key thing to note here is that the Trilobites only lived from 540 to 248 million years ago. And that the Ammonites were from 245 to 65 million years ago. So there's a 3 million year gap between these 2 different creatures where neither of them existed. So the dig where the trilobites were found has to be at least 3 million years older than the dig where the Ammonites were found. So with that in mind, let's look at the options and see what makes sense.
The rock layers must have formed at the same time because they both contain biozones.
* This is nonsense no matter what dates you're speaking of. In effect it claims that all rocks that indicate life were created at the same time. So this is definitely a bad choice.
The rock layers must have formed at different times because they contain two different biozones.
* This is technically incorrect since it assumes that all biozones represent an unique period of time which is incorrect. However, since the biozones represented by the presence of Trilobites and Ammonites don't overlap, it is true that these these rock layers were formed at different times. I would have preferred if this option said "non overlapping biozones". But on the balance, I'd consider this option to be true, so it should be selected.
The rock layer containing the trilobites must have formed before the one containing the ammonites.
* This is definitely true since the last Trilobite died about 3 million years before the first Ammonite lived. So this is a correct choice.
The rock layer containing the trilobites must have formed after the one containing the ammonites.
* This is the opposite of the previous option. And since the previous option was true, this option must be false. So this is a bad choice.</span>
