Footprints in Skamania County, Washington

I was near the top of Beacon Rock when I saw this thing climb the railroad bed in two steps. I had just climbed it an hour or so before and it took me many steps (I later did it again and it took 12). The railroad bed was a flat-topped gravel bed they laid the railroad ties and rails on. I guess to provide stability or drainage in the wet climate. This caught my attention. This large creature then set out across the meadow toward the river with long "keep on trucking" strides. It was huge. There were cows in the pasture and it walked between a few of them and it seemed as if the cows only came about 1/2 way up its body. It looked all black and I wasn't sure what it was at first. Trailing behind it there was a smaller creature which seemed to move like a chimp might move touching the ground with all fours. I thought it was a dog at first but closer examination ruled that out. We weren't really close so I had to do a little calculating, but the size of him between the cows and the 2 strides up the railroad bed made me think "bigfoot". He went to a little tributary of the river and squatted down for a while. I thought he was looking for salmon. I lost him for a while then he returned across the meadow. The cows were not in the least disturbed that I could tell, which was odd. We showed some other people on the rock, they were getting high however and could not be considered reliable although they charged down the rock to go look for it. We encouraged them to leave the creatures in peace. We returned the next weekend with my brother in law to see what we could find. It had rained that week however and no footprints were found. We did find some long dark hair on some barbed wire but I don't remember that we saved any. We have pictures of us with backpacks on that day, but hours of searching turned up nothing.