Answer:
Geolgic time is measured by observing the changes in the fossils from oldest to youngest sedimentary rocks.
Explanation:
The tropical forests can roughly be divided into two major groups, tropical evergreen forests and tropical deciduous forests. The division is made in accordance to the characteristics of the trees.
The trees in the tropical evergreen forests are green throughout all of the year. The reason behind this is that they have constant temperature all year long, and constantly high amounts of rainfall all year long, so there is no need for them to shed their leaves.
The trees in the tropical deciduous forests, on the other hand, are shedding their leaves. This means that in one part of the year these trees have green leaves, while in the other part of the year they are shedding their leaves and the branches are stripped. The main reason behind this is that the rainfall occurs only seasonally, when pretty much all rainfall for the year falls in few months. After that, a very long period of drought and very high temperatures starts. In order to survive and not get damaged, the trees are shedding their leaves, thus they almost put them selves in an hibernating phase until the next rainy season.
