Slippage cracks are crescent-shaped fractures or splits in the asphalt's surface layer (s) when fresh material has slipped over the underlying course. The reason of this issue is a lack of connection between the layers. When it rains, the water gets under the pavement and because there is no connection with the lower layer, it can't escape. This phenomenon can also occur with snow if the weight of the substance is great enough. The loss of traction caused by ice or mud can also produce similar results. These problems are commonly found in rural areas where vehicles tend to travel at high speeds and small stones are likely to be present in the road. The presence of these stones increases the pressure on the pavement and may cause a slippage crack. In cities, where traffic tends to be slower and pedestrians use pavements as walking surfaces, slip-slide cracks appear. These are linear fractures in the asphalt's surface layer caused by repeated movements of pedestrians' feet in shallow holes or dips in the pavement. The problem occurs when an insufficient thickness of asphalt has been applied during construction or maintenance efforts have removed some of the top layer. In either case, light traffic is recommended while repairs are being done. If you're seeing cracks in your road that don't seem to make sense, call in a professional.