When geographers observe more on ridge like piles of rock and debra's they conclude that

A glacier once covered the area

81 is a composite number

Historians are researchers of the past or people who understand the history of people. with this field, they must possess qualities such as being unbiased, patient, efficient reader, has a knack for logic and critical thinking and reasoning, disciplined, open-minded, resourceful, with good analytical ability, good reasoning skills and problem solving!