1. This research shows that the combined study of paleobotanical and sedimentological data from these deposits allows for a dynamic picture of landscape evolution in a relatively rarely studied tropical upland setting. In particular, this paper provides a first view of the dynamics of ecological succession in Paleogene forests of Africa subjected to repeated disturbance by major volcanic activity, such as those associated with rift development.
2. Analysis of macrofossils and sediments show that physiographic changes brought about by volcanism characterizing the Late Oligocene of northwestern Ethiopia influenced paleoenvironmental conditions and plant communities, transforming a forested landscape inhabited by riparian taxa to transient settings dominated by ferns and a few ecologically pioneer angiosperms typical of disturbed environments.
3. In summary, the common occurrence of ferns associated with only a few angiosperm taxa also known as ecological pioneers at several localities across the Chilga basin (100 km2) suggests that volcanism had a profound effect on plant communities over a large area. Therefore, it can be suggested that the extinction from the Ethiopian highlands of some angiosperms with affinities to modern West and Central African forests, present in older sediments at Chilga, could have been due, at least in part, to repeated volcanism associated with development of the northwestern Ethiopian Plateau.