Sealant and Monitoring
Borglum made it very sure to keep the base of this monument very strong, still it needed to be replaced with the time passing by. So the National park decided to replaced old sealant with new modern silicone. Wondering why silicone? Well I wondered same. They chose modern silicon because it has the capability of holding a wide range of temperature that the black hill face along with heavy rain and changing weather.
After replacing the cracks with modern silicone they made it very sure that they are not visible and they put granite powder on it. Electric monitoring devices were installed so that caretakers can foresee the damage before anything bad happens to the monument. These monitoring devices also helped them to monitor the temperature which may increase due to global warming in coming future. Monitoring it will help to be ready before anything happens.