Answer:
Due to erosion.
Step-by-step explanation:
An unconformity refers to a type of geologic contact that occurs boundary between rocks. The main causes of Unconformities is erosion, wears away rocks and rock deposits never form. The most common cause of unconformity is erosion in which the younger rocks spread on older rocks with the passage of time. In Cardenas layer, erosion is also occurs that leads to unconformity in that region which leads to the formation of boundaries in the rocks.