Read these sentences from the article. "Individual layers of ancient sediment form horizontal stripes on the rock. From a few steps back, the rock wall looks like a cross-section of a giant, stone encyclopedia." Why might the author have included this description of the rock wall?

Here's what I think  

Explanation:

They wanted you to understand that, to a geologist, the stripes on the rock are like the pages of an encyclopedia of information.

You start reading and getting information from page 1 of an encyclopedia, then go on to the next page, and so on.

In the same way, the lowest layer of stripes is the oldest and gives information on the earliest geological period. The layer above it gives you information on the next period, and so on.

i think its 100

i hope this !