The above map is an effort to illustrate the tar pollution
values at 53 shore locations on Tobago sampled
monthly from September 1980 to September 1981.
To get it all on a page, I had to make two modifications:
(ONE) Because concentrations varied over several orders
of magnitude (less than 1 to over 1,000 grams/meter of shoreline)
I transformed the values to the natural log, which allows
showing this range of figures on one single graph
see index on the right for values.
(TWO) What look like offshore values do NOT represent
distance from coast seawards, but instead show
time or seasonal variations from September 1980
"closest to shore" to September 1981 furthest "offshore"
see three scales perpendicular to shore.