Onshore correlation glass data for selected tephra units on São Miguel Island, Azores

A total of 44 gravity cores were collected in the Azores region in 2017, during the R/V Meteor cruise M141/1. Based on their length, content in tephra layers, and spatial distribution around São Miguel, 22 cores have been carefully selected as the most representative to gain insights on the volcanic history and the depositional marine environment around the islands of the eastern group of the archipelago. In total, 454 samples from 350 ash- or pumice/scoria/lapilli- bearing horizons were examined.