This is a puzzle cache. The cache is not located at the posted coordinates.
This geo-puzzle cache is part of a series of easy puzzles. The series is intended to get cachers involved that don't do geo-puzzles. Since the non-puzzler cachers usually don't include Mystery caches in their PQs, it would be appreciated if the rest of you would spread the word.
We are not talking about magazines nor the tides here. The periodical in discussion is the Periodical Table of Elements. This trick is often used for geo-puzzles, but usually not as simple as this one will be. Often the symbols will be buried in the text, maybe in bold. Or maybe in white text. Or maybe the start of various words. But, here you are dealing with just the basic premise of this type of geo-puzzle.
The final coordinates are: Ag Rb.SiC and MgHe H.ErH