原文 (英語)

INTRODUCTION Millions of people throughout the world have found many hours of pleasure, adventure and education by collecting either rocks or shells. This booklet won't tell you everything there is to know about rocks and shells. That would require many large volumes. We only want to arouse your curiosity about two delightful pastimes that are so broad and varied that they can lead to a career or a satisfying hobby. Shell Oil Company's interest in the subjects comes from its hi