Problem with time travel

The with time travel occurs to me, How do you know when you get there?

Basically a time machine would need some innate way of sensing when it is.    Normally we tell time using clocks, but  a clock only tells you how much time you've moved through since the last known point.

It's rather like sailing on the ocean before the days of GPS.    You would leave port, and measure the speed at which you traveled, and a chart would tell you where you should be based on traveling at that speed.    Without a landmark you never have a way of knowing where you are.  If you were wrong about your speed then you could be hundreds of miles off course.

Time doesn't offer us any known landmarks.   So it seems Dr. Brown's greater achievement than the flux capasitor was some discovery that allowed the DeLorean to know when it had to stop.

And here I thought nature was supposed to be relaxing

I sit here staring at this computer screen listening to the birds outside my window. They sound as though they are screaming at each other. I can tell they are fighting, fighting over food, over territory, over mates. I watched a hummingbird try to scare away a much larger oriole from the feeder. So much for the relaxing sounds of nature.