They are useless for common agricultural purposes.

In several the culture of coffee has been begun; but they are so inaccessible, the roads into them are so difficult, and the area of arable soil they contain is, after all, so insignificant, that, even for so valuable a product as coffee, transportation is found to be costly.
But it is along and in the streams which rush through the bottoms of these narrow gorges that the Hawaiian is most at home.

Go into any of these valleys, and you will see a surprising sight: along the whole narrow bottom, and climbing often in terraces the steep hill-sides, you will see the little taro patches, skillfully laid so as to catch the water, either directly from the main stream, or from canals taking water out above.
Such a taro patch oftenest contains a sixteenth, less frequently an eighth of an acre.

It consists of soil painfully brought down from above, and secured by means of substantial stone walls, plastered with mud and covered with grass, strong enough to resist the force of the torrent.

Each little patch or flat is so laid that a part of the stream shall flow over it without carrying away the soil; indeed, it is expected to leave some sediment.