We are studying if turtles use magnetic field for navigation. Different components of magnetic field (inclination, declination, total intensity etc.) are visualised as isolines. Recent studies show that mostly animals use inclination and total intensity. Those isolines are different across the globe. If they are paralell to each other animals can use it to travel just in one dimension, but if they are not parallel (even if they don't intersect) animals can use it for bidimensional navigation. So I was wondering if there is posibility in ArcGis to classify areas with parallel and not parallel "inclination" and "total intensity" isolines. I found both inclination and total intensity as shapefiles for ESRI . Thank you!