Georgia State Parks is sponsoring "Leaf Watch 2007," an online update on the fall foilage at some of Georgia’s most scenic state parks and state historic sites. Each week, rangers send updates on how the leaves look at that particular time. Lace up your hiking boots and come enjoy Georgia's state parks this fall. Better yet, bring along the family to walk off those Thanksgiving calories.

WHY LEAVES CHANGE COLORS

It’s a common misconception that Jack Frost causes trees to turn colors. Actually, freezing temperatures can shorten the length of time that trees are most vibrant. Experts predict this will be a great season for color, although hurricane winds have blown many leaves down prematurely. During spring and summer, leaves serve as food factories for trees. This process, called photosynthesis, takes place in the tiny leaf cells that give leaves their green color. These chlorophyll bodies make food by combining carbon taken from the air with hydrogen and minerals found in water gathered by roots. As the days shorten and the nights get cooler, a chemical clock kicks in and releases a hormone that slows the sap flow to each leaf. Eventually, the leaf is sealed off from the branch and the green chlorophyll fades away to reveal other pigments - colors that have been there all along. The Native Americans had a fantastic idea that leaves changed color because celestial hunters had slain the Great Bear, with his blood dripping on the forests and turning leaves red, and fat splattering out of cooking kettles and turning other leaves yellow.