These are some pictures of a log arch I had a welder buddy of mine build for me about 6 years ago. I would like to be able to take credit for designing the arch, but I saw an advertisement for a commercially made one in a logging magazine. I just cut the advertisement out and got a set of wheels and spindles from a junk yard and gave it all to the welder and he went from there.
The top of the arch lowers to the front. You wrap a chain around the logs and hook to the top of the arch. As you pull forward the arch held by the weight of the logs will raise lifting the front of the logs up so they won't dig in the ground.
To lower the logs to unhook the chain, you just back up a little and the arch folds forward releasing the tension on the chain. I usually just put a short log under the towed logs and as you pull forward it raises the logs and again releases the tension on the log. The arch supports the majority of the weight with the pulling vehicle only used for towing the arch with the logs.
For years I used my pick up but this little tractor does a great job. As you can see I had scooped some sand in the front bucket to help keep some weight on the front wheels.
A word of caution here, whenever you pull logs up a hill or steep rise go straight up and not sideways across the hill. If you try the sideways route the logs may try to roll and the weight of the logs may cause the arch and possibly the tractor to upset.
The first picture is of one pine log about 24 inches in diameter at big end and 16 foot long. According to http://www.woodweb.com/ the log weighs about 2,000 pounds.
The other pictures are of the arch with 2 pine logs one 16 foot long and the other 20 foot long. Both together weighed about 3,000 pounds.
I pulled them about 700 feet (2 1/3 football fields) from the front of my property to where I keep my sawmill. I was able to get 60 feet of logs out of this one tree - one eight foot, two 16 foot, and one 20 foot one. We (or rather mother nature) can go grow the heck out of pine trees here in the red clay of Georgia.