D. unique in its appearance. Index fossils must have a unique form that is easy to identify without special equipment. Geologists make maps in the field as they gather data and specimens. If the index fossil is easy to identify without the use of a microscope or laboratory equipment, the field work can process more quickly.
Answer:How do these ideas connect to the first two paragraphs of his letter? ... Assessed Standard(s) RI.9-10.3 Analyze how the author unfolds an analysis or series of ...