What are gaps in rock layers called?

According to the Institute for Creation Research, the gaps found in rock layers are known as “unconformities.” They represent erosion or a time period known as non-deposition.

Rock layers are usually dated using their specific fossil content, which is arranged in an order known as erroneous evolution. Geological columns are not considered to be accurate history, but rather a statement of evolution. There is, however, some truth contained in geological columns. Geological columns are used to present rock records through different ages. It may seem authoritative, but it is not recommended by the Institute for Creation Research to rely on these too much.