As well as being the area within the Arctic Circle, the Arctic can also be defined as being the area above the "treeline" (farther north than trees can grow), where there is only tundra and the Arctic Ocean.

Why don't "standing ups" grow here?

1.   The very short summer, lack of sunlight, and not enough days of temperatures of at least 50°F / 10°C don't allow large trees to complete an annual growth cycle.

2.   The ground is always frozen beneath the top layer of soil (permafrost), so trees can't send their roots down far enough to keep the tree from falling over!

3.   The harsh, bitter wind carries sharp crystals of ice that cut and kill trees. The treeline on the map is not a straight line - it fluctuates, largely depending on the force of the cold Arctic winds.

But is wasn't always that way. About 45 million years ago, some Arctic areas were covered with dense forests of trees that rose about 120 feet / 40 meters.

Some of those trees have been preserved, not as coal or petrified wood, but still as wood and leaves - less than 700 miles / 1,100 km from the North Pole!

Scientists have an opportunity to figure out the ancient climate, and perhaps to predict the effects of future climate changes.