When soil water freezes and forms ice layers parallel to the ground surface, it causes the soil to heave or move in an uneven manner. This happens because water expands when it freezes, and the expansion creates pressure within the soil. As a result, the soil is pushed upward, causing it to heave.

Option 1 is the correct answer because it accurately describes the effect of freezing soil water. The heaving occurs in an uneven manner because the ice layers are not uniformly distributed throughout the soil.

Option 2 is incorrect because freezing soil water does not cause the soil to heave downward. The expansion of water when it freezes creates an upward force, not a downward force.

Option 3 is also incorrect because it suggests that the soil heaves both upward and downward in an even manner, which is not the case. The heaving is primarily upward and is not evenly distributed.

Option 4 is incorrect because freezing soil water does have an effect on the soil. It causes heaving and can disrupt the stability of the ground surface.

In conclusion, when soil water freezes and forms ice layers parallel to the ground surface, it results in the soil heaving upward in an uneven manner.