Communications at Work 
Here are two scenes. One is the work of nature; the other, the 
work of man and nature in partnership. Examine the accompany- 
ing texts and see how each is intended to develop in the reader an 
appreciation for the scene. 
SENTINELS OF TIME 
Many of these bristlecone pines were living when the pyramids 
of Egypt were built and they are still living today. By surviving for 
more than 4,000 years they have earned the distinction of being the 
oldest known living things on earth. 
Here they stand silhouetted against the sky, gnarled with age, bat 
tered by the centuries, clinging to life in a harsh environment. 
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