One theory is that in order to move the giant heads from one part of island to the other itrequired them to cut down trees to use them as rollers to roll the heads down to the edge of the island. As each generation sought to make a bigger and better statue, it required that more trees be cleared. Eventually, the forest disappeared.
Although most states had established public schools by the Civil War, many school-age children still received no formal schooling. The majority of students who went to school left within four years, and only a few went to high school. <em>Between 1871 and 1920 there was a drop in literacy levels in the U.S. where it's estimated that by 1920 there was a 92% literacy level (21.6 Million) in the U.S compared to 80% (9.9 Million) in 1871.</em> College enrollments rose to more than four times as colleges initiated significant changes in curricula and admission policies. The industrial development had changed the nation's educational needs. During this period thousands and thousands of adult immigrants attended night school to learn English and to qualify for American citizenship.
B .........................
Could we have a look at the sources?