"But it wouldn't bring down enough to make all that field, would it?" asked Donald.
"The river is a great worker," said Uncle Robert. "It is at work now, and has been working for many, many long years. It has not only made this flood-plain, but many others. Sometimes the river carries this dirt clear out into the sea, and sometimes it piles it up at its mouth so that a delta is formed."
"Oh, yes," said Donald, "we studied about that in geography when we had school, but I didn't know a delta was made that way."
"Are there any deltas in this part of the river?" asked Susie.
"There may be," replied Uncle Robert, "wherever one stream flows into another."
[Illustration: The mill and dam.]
"Is there one at the mouth of our creek?" asked Frank.
"We will look when we go back," replied Uncle Robert. "Shall we take a walk now?"
When they reached the upper end of the island they sat down on some large boulders that formed part of the tiny beach. Just above them was the flood of water pouring over the dam. The bright sunshine made the foam look white and glistening, lighted here and there with colors of the rainbow.
The water rumbled and roared as it rushed out of the mill pond. To the left were the flour mill and the village. They could hear the mill wheel turning. They could see a little white church half hidden among the trees.