The ice is a 115,000-year archive of atmospheric gases, dust and other chemicals from the time the snow first fell. A chart shows the effects in the ice of the eruption of Vesuvius in A.D. 79 and the Clean Air Act in the United States, beginning in 1974. Some of the rock specimens can be viewed as a natural art form as well as a lesson in geology. The rippling folds exposed in one rock cutaway are a graceful show of how seemingly brittle material can flow, given enough time and heat. One approaches a polished specimen of banded iron from Ontario, 2.7 billion years old, with the same impulse.
Fingers run over the dark red streaks of jasper.
Helpful labels explain the deeper meaning. When single-celled organisms began supplying oxygen to the earth' s atmosphere, iron and silica minerals emerged out of the ocean. The red bands in the rock stopped forming once the atmosphere and ocean were saturated with free oxygen. Here, then, were rocks telling of this fateful transition in an evolving earth. Another display brings together two sandstones that were, so to speak, separated after birth.