Why exactly is the Sphinx more in danger of deterioration than the Statue of Liberty?

Atmospheric, Groundwater and other modern pollution is the reason why the Sphinx more in danger of deterioration than the Statue of Liberty.

Explanation:

The depletion of the resources like the Sphinx and other valuable historical monuments were due to the modern pollution. The monuments like the Sphinx and the Gaza Pyramids is situated across the region of Mediterranean. The main reason for the deterioration of these monuments were the atmospheric and the groundwater pollution. Unless these pollution is controlled it will be very difficult to save these monuments.

In the statue of Liberty, the head portion and the neck portion are the parts that were exposed to the erosion process. The neck of the statue is eroded and hence the head is in the danger of falling. This is because these areas appear to be very weak and hence they may get damaged once they were exposed to elements that are erosive in nature. This risk can be reduced by preventing the exposure of these parts from the erosive elements.