The first layers of the last deposit were alternating belts of light and dark-colored material, and were densely welded. They appear to have been erupted in pulses, and continue for hundreds of meters. Deposition was continuous except for one interruption, which can be seen at proximity to the caldera, where the layers are replaced by thin, nonwelded sheets of lava. Another zone of nonwelded material, about and near Cajon Los Calabozos, underwent no erosion, suggesting that activity stopped, then began again.