Fire suggests resurrection, which involves a transformation of form without dissolution or the slow process of decay. Flame is a process, a chemical reaction. Life to ash, spread on fields, yields increased life. Water in symbolic terms, suggests the sum of all virtualities and possibilities. In mythology the waters are said to have existed before earth.
Waters abolish form through dissolution and give rise to new forms through precipitation.
Having said all this I must caution against believing that the response of all human minds to nature is uniform, especially at the level of specific interpretation. When we realize that a given symbol changes in meaning and emotional charge for an individual even over one lifetime, it becomes strikingly clear that natural phenomena as symbols do not mean the same thing to all people in all cultures throughout all eras. Reactions to nature are conditioned by culture and history. Many differences can be explained by variations in economy, subsistence patterns, culture and social organization. The same can be said of sacred places in nature.