Geologists have recently determined that the minerals goethite and hematite exist in abundance on Mars, sure signs of the presence of water (see Figure 1 for a picture). None of those geologists have been to Mars, of course, but the unmanned rovers Spirit and Opportunity have. These rovers are equipped with three mass spectrometers, each of which is capable of determining the chemical composition of a solid with a high degree of accuracy. With such a precise chemical analysis in hand, geologists on Earth had no problem identifying the minerals.
A mineral is defined in part by a specific chemical composition. In theory, therefore, it is always easy to identify a mineral, if you can determine the chemical composition with a mass spectrometer like the Mars rovers. In reality, however, even if you are looking at rocks on Earth, determining the exact chemical composition of a substance involves significant time preparing the sample and sophisticated laboratory equipment (and often significant money). Luckily, it is usually unnecessary to go to such lengths, because there are much easier ways that require little more than a magnifying lens and a penknife.
Rivers provided food and fresh water, as well as fertile soil that would be suitable for growing basic crops.
There are 109-women 135-man
Answer:
They are classified by altitude and the patterns they form.
Explanation:
Clouds are classified by their altitude in the troposphere. Some clouds are found beyond the troposphere. The classification as surface level, low, middle, high and multi-level. The multi-level are massive storms clouds, known as cumulonimbus that rise from the low altitudes to the top of the troposphere. A surface cloud can be classified as fog or mist. The low level can have stratus clouds. The middle level can contain nimbostratus and the high level can contain cirrus clouds. The names are given based on their altitude but the way in which their form.
