If i may add my 2 cents worth, as a qualified trainer with ten years experience, Mark Hill and Dragonfire are correct.
Squats and deadlifts pose problems to a developing spine if done with poor technique- this usually results from using too much weight. Safe logic is to concentrate on crisp technique, preferably in the presence of an experienced spotter. If in doubt go lighter for higher reps with spinal load exercises (squat, deadlift, overhead press and bent over row) until you are pretty much fully formed (usually 17-18 years old).