. The Earth beneath the sea : History . Fig. 12. North Mahavavy delta, Madagascar, showing a braided-channel pattern. (Photo. A. Guilcher.) part played by wave action on the delta front: it may be supposed that it would be of very small extent, because the sea is frozen at the time when waves could overcome the river forces. Another type includes intertropical deltas in which disastrous floods occur owing to the great rains which fall over large areas during hurricanes or ty|)hoons. The North Mahavavy delta in the north-west of Madagascar belongs to this type (Fig. 13). Each big hurricane resu
. The Earth beneath the sea : History . Fig. 12. North Mahavavy delta, Madagascar, showing a braided-channel pattern. (Photo. A. Guilcher.) part played by wave action on the delta front: it may be supposed that it would be of very small extent, because the sea is frozen at the time when waves could overcome the river forces. Another type includes intertropical deltas in which disastrous floods occur owing to the great rains which fall over large areas during hurricanes or ty|)hoons. The North Mahavavy delta in the north-west of Madagascar belongs to this type (Fig. 13). Each big hurricane results in a new course. The channels are braided and basins exist as distinct units. The sediments in channels are of two types: coarse sand deposited during floods and fine sand, silt and some clay deposited during low discharge. Micaceous silts of low density are found on levees. The clay content is a maximum in the basins, although coarse quartzose elements are present. On the seaward side, between meandering tidal creeks extensive mangroves grow on mud which includes an important coarse fraction
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