Your eye is caught by a massive outcropping of rock. You approach to get a better look at how the plants could possibly find root in cracks and crevices, and then you see the opening, large enough to enter.
Curious about what’s hidden inside, you advance cautiously, feeling the slightly rough texture as you let your fingertips graze the sides of the tunnel.
Noticing a spot of brightness overhead, you look up to a reassuring glimpse of sunlight and sense more than see the movement of foliage at the surface overhead. You realize that the forest sounds have become remote as your ears tune to a gentle trickle of water coming from somewhere ahead. And then a slight bend leads you suddenly into a much larger space: you’re in a cave.
Surprised? We hope so. The cave is actually inside the Vale Earth Gallery at the Canadian Museum of Nature, and you’ll be able to explore it after the gallery re-opens on November 30, 2012. We’re in the midst of completely re-doing it now, and the cave will be a stunning new feature.
Of course we think that visitors will enjoy the experience and learn interesting things about limestone caves while they’re at it, but the process of developing and constructing the cave has also been fascinating.
It all started with a well-developed concept by a multidisciplinary museum team. The plan accounted for the visitor experience, educational goals, and, of course, the natural history of caves.
Next, different members of the team made a clay model and a storyboard. These representations were shown to the company that was hired to create the cave, to help them get a very solid idea of what we were after. Research Casting International started by making their own clay model, and the cave itself is a faithful, scaled-up version.
Fabrication began in the RCI workshop with the steel “cage” that supports the walls and ceiling. Steel rebar for the walls themselves was formed into shape and temporarily attached, and then removed again for transport to the museum.
Once in place, the structure was covered by a metal mesh that formed all the contours of the walls and parts of the ceiling. The mesh serves as a substrate for the concrete that RCI sprayed on to make the fake limestone. In addition, several parts were cast from a real limestone rock face. The museum team is a bit in awe of the artistry that went into creating such realistic shapes and surface textures.
Limestone caves are carved by water, which both removes rock and adds subsequent formations. The mild acid in groundwater dissolves the rock and the water carries it away, thereby eroding cracks into caverns over millions of years. The water also allows the opposite to happen: dissolved limestone can slowly precipitate out of solution, re-solidifying as secondary mineral deposits that grow in caves in a host of bizarre shapes.
Just as a cave is first carved out and then new formations grow, once the museum’s main cave envelope was in place, RCI’s talents were turned to the applied features. Columns, stalactites and stalagmites are of course represented. But you’ll also see formations with evocative names: draperies, popcorn, pearls. They almost give new meaning to the term “concrete poetry”!
Caves are not just about geology and hydrology: they contain complex living ecosystems, too. The practical matter of the amount of space available and the need to keep the focus on the geology, however, limited how much the museum team could get into cave life. Accordingly, they decided to depict a few temporary cave guests—animals that use the caves, but don’t live there exclusively. The team and RCI are just now at the stage of finalizing and fabricating these trogloxenes, as they’re called. Needless to say, there’ll be bats. And, we’re hiding another mammal as a surprise for young visitors to find.
The last artistic stage has a dramatic impact: when the cave walls are painted to resemble limestone, the realism suddenly brings the cave right to life.
Final, prosaic finishing details include the installation of mechanicals such as sprinklers, lights and cameras. Yes, even building safety codes need to be considered in the development of an enthralling, immersive experience for museum visitors. But we don’t think it will be hard for you to suspend your disbelief when you enter the beautiful new cave and turn your imagination to marvel at the dynamic systems that shape the Earth beneath our feet… and sometimes overhead!