The golf swing takes place so rapidly that it is often impossible to detect the key mistake that causes a bad shot. There is one way, however, to find some important clues. You can compare the direction of the divot mark with the trajectory of the shot.
The most obvious example of what I mean is supplied by the divot mark that cuts across the line to the target from right to left. This significant mark in the turf has obviously been created by an outside-in swing. If the club face was closed at impact the shot will be pulled to the left. If the club face was square, the shot will slice.
But more subtle clues to faults in the swing can also be found in divots. If the divot mark goes straight toward the target but the ball goes to the left, it has probably been hit with a closed club face. This is usually the result when too much right hand has been applied to the shot just before impact. If the divot mark is straight but the ball starts to the right and slices even farther right, the ball has been hit with an open club face. This is often caused by the hands getting too far ahead of the ball at impact. If the divot mark starts straight and then veers left you have probably shifted too much weight on to the left foot and let the left side give way—or collapse.