CalTopo - Use the “Bearing Line” tool as a peakfinder
(If you want to learn the basics of using CalTopo, start with this tutorial video.)
One of the eternal things climbers love to argue about sitting on a sunny mountain top is the game of “What's that peak?”
Now, you could use a clever smart phone tool such as the app “PeakFinder”, but here’s another method.
Take a compass bearing from where you are to the mountain top (or other landscape feature, like a lake.) If you just have your smartphone, there should be a compass app on that. Take a screen grab to remember the bearing.
When you come home, open up CalTopo.com on your desktop, Right click the location where you took the bearing, and choose New > Bearing Line.
Enter the bearing and distance in the dialog box. Usually you don’t know how far away the peak is, so enter a huge distance, like 100 miles.
CalTopo will draw a line from the start location on the bearing and distance you specified. If it runs through (or close to) a major mountain, you have your answer.
Here's a recent real life example. A friend of mine who lives in Bend Oregon took a walk to the top of Pilot Butte one evening, a local high point in town. Far off in a general SW direction, he saw the tip of a mountain pointing up that he had never noticed before. What could that be? He took a compass bearing to it, and the resulting CalTopo bearing line map looked like the top of this page.