Just as optical images can be displayed, so can 2-dimensional maps of otolith data. We typically raster a beam across a sample and apply one of several methods to quantify concentrations of trace elements or isotopes. In the example below, I show data from an otolith of an Atlantic salmon. What is obvious here is that strontium (Sr) and zinc (Zn) are incorporated in very different ways. Each has a story that took me a long time to figure out. The Zn map is actually an example of what I call an "otolith chemical calendar-clock." The Zn is high (dark reds) when the otolith (and the fish) are growing quickly, as in the summer. Low concentrations occur when growth is slow. Thus, the salmon's otolith zinc can tell us about seasonality, and we can match up the chemistry of, say, the strontium to understand what season or year the strontirum changed (which is caused here by the salmon moving from one habitat to another).