4900
The mountains were originally contiguous with the higher Sawatch Range to the west but were separated during the formation of the rift valley at the headwaters of the Arkansas River approximately 35 MYA .
 location: Sawatch Range; location: Arkansas River
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:
 location: Sawatch Range; location: Arkansas River