1. use the lake san cristobal, colorado map to answer these questions. this area is in the san juan mts, of co. the rocks are tertiary volcanics, this means they are young in age and poorly consolidated. they are composed of andesites and pyroclastic rocks. the rocks decompose and weather very easily. a. lake san cristobal is only 700 years old. how do you think lake san cristobal originated? b. based on the information provided above, what type of movement would you classify the slumgullion slide? c. what type of material do you think is most likely involved in the slumgullion slide? d. the slumgullion slide is actually composed of 3 separate slides and is still forming. for the past 300 years, the active part of the slide has been flowing down from the base of mesa seco over the top of the older slides. currently, the toe (bottom) of the two-and-a-half mile long active slide is about 1/8 mile above the road where highway 149 crosses the older portion of the slide. while the fastest parts of the earth flow move eighteen feet per year, recent studies have shown the toe to be advancing about five feet per year. calculate how long before the highway department has to deal with this slide.