Some fossils, like this trilobite, are considered fossils. This type of fossil is used to help match the relative age of rock layers. In order to do this, the fossil must be found in many different places, during one time period, and have some unique characteristics.
A) C-14
B) Index
C) Trace
D) Stratified

This is a 2017 topographic map of puerto rico in the united states, and i'm sorry that people there have suffered such a disaster. i want to ask, what do the yellow dots and areas represent on this graph? and the blue area and the little blue circle, and the little blue sign that looks like a signal tower, what do they stand for?