Geeze, if only I would have really paid attention in those Science classes rather than staring out the window and daydreaming. Perhaps I would know the answer to this question based on a recent observation from the field.
My wife took a series of photos of rocks adjacent to a lake. The images clearly depict a water line of sorts.
So, I researched littoral zones, eulittoral zones, lakes, vegetation, high water, Southern exposures, lichen, types of rocks etc. Why does nothing grow upon the rocks below the high water marks? The water is well below this mark for many warm months during the Summer. The water doesn’t rise up to this level for many months after Summer. Snow/Ice covers much of this area at times. I just wonder the why of it.
My wife took these images not with that question in mind, but rather she intuitively sensed the contrast and starkness of it all in a harsh environment. Perhaps someone with a greater grasp of science or more common sense than I can answer the question?
SwittersB & Exploring 
I like the fact that you have such an enquiring mind as much as the explanation of this phenomenon. I think that all the better fly anglers I have ever come across have this sort of mind set. “Why?” is such a powerful question, it separates those fascinated by the world from the intellectually incurious. In the end I don’t think that finding out the answer is necessarily as important as posing the question.
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Thank you Tim.
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If the water level does reach those levels for even a couple of weeks in each year, that would be enough to prevent growth of lichens and moss… Lichens and worts are extremely slow growing and their presence helps indicate the prolonged absence of acid rain and other pollutants… snow on the other hand, does not pose the same threat as water, in that it still allows a degree of airflow and respiration – hope this helps & happy to be educated otherwise!
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Thank you!! I knew there would be a smarty pants out there.
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Ha ha, definitely not smarty pants Mr SwittersB – just someone who is grateful for your awesome blog and what it stands for! Kind regards – metiefly
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