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The softer layers of sandstone beneath the basalt sheet eroded over time , creating pathways behind some of the waterfalls that Civilian Conservation Corps workers widened to make safe for public use .
 organization: Civilian Conservation Corps
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 organization: Civilian Conservation Corps