**I climbed the hill...**... and just a bit more down the path, I climbed another one just like it. A bit more down the path, ANOTHER one just like it. Interesting--how long would this repeated series of seemingly identical hills go on?

As I flew across center part of the US yesterday, I had a window seat and able to peer out the window for much of the flight. What I saw amazed me, and it reminded me of that repeating hilly path. I kept seeing waves upon waves of stone and sand, patterns written in the geography.

One of the problems we have as writers is knowing how to describe places in ways that are evocative AND descriptive enough that you get a great sense for what it's like to actually be there.

I can tell you the path I was on was a jungle path, or a desert path.. but it's hard to be precise about the path

*per se*.

Tony Hillerman might write "...the eroded flanks of the hills covered with an infinity of dark green creosote bush and the grey-white desert grasses...", or Hemingway could say "... Hills terraced and yellow fruit shining through the green leaves and darker green of olive trees on the hills, and streams on the hills, and streams with wide dry pebbly beds cutting down to the sea and old stone houses, and everything all color." These are beautiful, but vague.

Face it, I've got an engineering heart (wrapped in the pulsing body of a poet), so I'm looking for something a bit more.. precise. How far apart are those hills? How high and low do they go?

Here's one of the sights I spied from my window seat (this is part of Point Reyes, CA, near Bolinas Lagoon). Note the repeated foldings of the hills. That's a lovely pattern--now, how can I describe it?

Here's a map of that same area:

As you can see, the streams are all parallel, telling us that the hills and valleys are all parallel as well--repeated ridges marching next to the San Andreas fault.

Now suppose you drew a line like this across the tops of the hills, streams, and valleys:

If you drew the cross section of this piece of the land, you'd see something like a sine wave,

As you know, a wave like this can be neatly described by its

*(how many up/down cycles happen per unit time, e.g., 440 cycles/second), and its*

**frequency***(how for up and down the wave goes--in this case, the amplitude for the sine wave above is 1--it goes 1 unit up from the centerline).*

**amplitude**Now, if I want to describe these hills in Point Reyes, I thought about describing them in terms of their

*frequency*. Some hills have a high frequency, while others have low frequency, but a high amplitude.

With just a couple of searches, I was able to figure out the answer to today's Challenge. Can you? This Challenge comes in a couple of parts. Even if you can't figure out how to do parts 1 and 2, EVERYONE can do something on part 3.

1. Does the term "frequency" make sense when applied to repeating hills?Frequency is usually defined as cycles / unit-time. Can you figure out how to apply the concept of "frequency" to hills?

2. What's the frequency (however you define it for hills) of this stretch of hills above?You'll have to find it, measure it, and then figure out the "frequency," if you can!

3. Can you find a stretch of the Earth that has a nicely repeating pattern to it similar to the one above? If so, where is it?(Give us the lat/long in your answer.)

As always, be sure to tell us HOW you found the answer.

I can't wait to see what glorious hillsides you'll find! (Be sure to tell us how you found them. Did you just

*know*about them? Or did you actually do some kind of search?)

Search on!

*P.S. I will be traveling again next week when the answer is supposed to come out. I might not be able to get to an internet connection to post my result. But stay tuned... you never know... I'll definitely post how I solved it.*