Dry stone from the arable or cultural land. They serve both as cattle/sheep fences and the lot's borders. Sometimes also the dry stone terracing is apparent, often combined with parts of stone masonry (house foundations and shed walls) that are held together by a clay-cum-needles "composite" mortar. In Peru in the 15th century AD, the Inca made use of otherwise unusable slopes by building dry stone walls to create terraces. They also employed this mode of construction for freestanding walls. Their ashlar type construction in Machu Picchu uses the classic Inca architectural style of polished dry-stone walls of regular shape. The Incas
Geometry from the Land of the Incas Geometry from the Land of the Incas Geometry from the Land of the Incas is a free geometry website funded by advertising, aimed mainly at high school and college age students. Developed by Antonio Gutierrez, the site uses sound, dynamic geometry, animations, science, and Incan history with the goal of raising students' interest in Euclidean geometry. Numerous problems are presented with step-by-step solutions for each proof. Around 2003, the website won several minor awards from educational publications, including One of the Top 10 educational Web Sites Canada's SchoolNet's in 2003 , the Knot #284 Canadian Mathematical Society , NCTM Illuminations