positioning in order to allow gravity to move the water from its source to the crops. The slopes allowed the water to travel easily and reliably to the crops in order to make sure they had the water they needed in order to flourish. The water that travelled along the canals was drawn from small streams. Crops had been planted in areas that were lower than the rivers although they were not naturally wet. This showed that the civilizations which utilized the canals were organized enough to notice their surroundings and use the geography to their advantage, rather than simply choosing random areas to plant their crops. Although the canals only date back by as much as 6,700 years, many scientists believe that there may have been an organized system of irrigation as much as 9,000 to 10,000 years ago although they feel that evidence of these very early canals will be hard to find. References Science and technology in Mesoamerica Pre-Columbian cultures History of the Americas