Answer:
Organic matter
Step-by-step explanation:
As organic matter continue to build up in a pond, vegetation will begin to appear in the pond. The first set of vegetation to appear are the floating vegetation. Subsequently, submersed plants begin to grow also.
With time, organic sediments continue to fill the pond and its depth is gradually decreased. A swamp or bog is now formed.
This trend of succession continues until the pond eventually turns into land.