Horizon is good trail. Kind of a mini turkey mtn.
Anyway. I assume you presta valves? If so buy the Slime brand tubes that are already slime filled. That will solve the problem. They will be heavier than your regular tubes, if that is a concern.
If your tubes have schrader valves just go buy a bottle of slime and pull the stem and the correct amount.
Also, if you are pinch flatting add more air to the tires.