G4 – The Hidden Secret to Skyscrapers On grade -03
Just like a building’s structure, the area the building sits on must also be well constructed. In other words, the ground needs to have the strength to support the building’s immense weight. Some areas may have bedrock close to the surface, but the bedrock itself is soft or fragile. For example, some sedimentary rocks are made from the shells of tiny creatures. This type of rock can support the weight of some smaller buildings, but its strength is no match for some of the world’s tallest skyscrapers. Other types of sedimentary rocks may include caverns, which could collapse under the weight of a large building. Even other areas have bedrock buried under a very deep layer of soil. Just digging down to the bedrock might become too expensive of an undertaking.
There are a lot of Mathematics, Science, and Engineering that goes into designing super-tall buildings. One of the first things an engineer will want to know is on what type of surface the building will be built. The physical properties of the soil or rock that make up the surface will determine the shape and height of the building.
On softer soil, the building may not be able to be built very tall. Instead, the architect may need to design a building that will distribute the huge mass or weight over a larger area. It just so happens that the bedrock under New York City is extremely hard and durable as compared to many other areas. The land near New York City is composed of a very dense type of rock called metamorphic rock. The word “morph” means to change; therefore, metamorphic rock is a type of rock that has been altered by intense heat and pressure deep inside Earth’s crust. Metamorphic rock can be formed from either a sedimentary rock or an igneous rock.
The rock layers under New York and the surrounding area were once sedimentary rock. Around 400–500 million years ago, geological activity caused the rocks to become buried deep in Earth’s crust. It was there that they morphed, or changed, due to extreme heat and pressure. They were changed into the type of rock they are today, the Manhattan Schist. This newly changed rock can handle the huge weight of super-tall buildings. It was this geologic event millions of years ago that now makes New York’s impressive skyline possible. As it turns out, how tall you can build a building is a combination of money, Engineering, and the ground it will set upon.