text: This is thought to result from the sublimation-driven degradation of small landforms , which is supported by the general deficit of small impact craters and the presence of numerous small knobs , considered to be their remnants .
simplified: This is thought to result from the degradation of small landforms , caused through sublimation , which is supported by the general lack of small impact craters and the presence of numerous small knobs , considered to be their remains .