A beach ridge plain in Coquimbo Bay, Chile, was studied using luminescence dating. The research found that the beach ridge plain was formed between 5000 and 4000 years ago, with a rapid progradation period lasting about 1000 years. The beach ridges are 8 to 10 meters above sea level, likely due to factors like eolian cap build-up, wave runup, and tectonic uplift. The findings suggest a stable shoreline over the last 4000 years, with evidence supporting a mid-Holocene sea-level high stand.