This weekend, I did a wee hike I've done many times before. It's slightly less than 7 kilometers from the parking lot at Upper Lynn Canyon to the falls on Norvan creek (PDF warning). The path starts very wide, and is paved with gravel. After the cache point where the upper and lower trails combine, it's narrower and just dirt, with occassional stretches of courduroy wood "paving" or log-type bridges. The elevation gain is about 400 meters, but the gradient is always shallow. It's a pretty fast hike; I did it this weekend in about 3 hours round trip. 14km / 3hours = 4.67 km/h, a very fast walking speed. Anyways, I've done that hike numerous times, and every time I pause to admire a particular rock, at around the 2.0 km mark, and I'm always careful to step directly on it. Here's a picture:
And another, from the side:
You can see it's quite pointy and sharp, which is probably why I always notice it.