In Japan, as in Europe, three varieties of relief carving are distinguishedalto (taka-bori), mezzo (chniku-bori) and basso (usunikubori).
The eastern depression, known as the East African trough or rift-valley, contains much smaller lakes, many of them brackish and without outlet, the only one comparable to those of the western trough being Lake Rudolf or Basso Norok.
They can be played either by violin alone or with the basso continuo accompaniment which is reproduced at the bottom of every page.