For Real?

Were these boulders made by mother nature or a designer at the North Carolina Zoo?

Imagine going to the zoo, looking into the elephant exhibit, and you see something that looks like a tree or a termite mound or a boulder. It looks completely normal and natural. In reality, the tree or the boulder is made out of steel and concrete by a group of artists. Why steel and concrete? Because a large animal can do a lot of damage to a real tree in a very short amount of time. By using steel and concrete, the tree lasts.

The artists start with a sketch – for example, a sketch of a termite mound. The sketch gets turned into a plaster model showing what the mound will look like in three dimensions.

A designer at the North Carolina Zoo shows us a small-scale model of an ant mound.

This model is cut into slices, and the slices give the artists a pattern that lets them create a full-size steel frame. Once the steel frame is welded together, it is the same size, and the same general shape, as the termite mound. This frame is covered with a wire mesh, and then the mesh is sprayed with a type of concrete called shotcrete. While it is still wet, the artists can impress the shotcrete with patterns. For example, if they are making a tree, the artists can impress the shotcrete with rubber molds that are taken from real tree bark.

Photo Courtesy North Carolina Zoo Spraying shotcrete at an exhibit site at the North Carolina Zoo

Inside a fabricated tree

After the shotcrete sets, it is as hard as a rock. Now it is time for paint. The paint can be very detailed, so it looks like stone covered with lichen or tree bark covered in moss and the occasional bird dropping. By the time it's moved into the enclosure, it is nearly impossible for visitors to tell a concrete tree or boulder from the real thing. So the trees look real – but the elephants can't destroy them.

We were amazed by how real these tree limbs look - even up close!