Random unsubstantiated theory. I recall reading a book on the Celts which revealed that they actually had substantial technology before the Romans arrived. One

Random unsubstantiated theory. I recall reading a book on the Celts which revealed that they actually had substantial technology before the Romans arrived. One of the innovations was a carefully operated defense network whereby shouted messages were repeated across long distances such as quiet valleys in order to distribute general news or to summons geographically disparate tribes in the event of invasion. Since Celtic culture was substantial in the area, could the sites be related to the placement of messaging centers? An intertidal zone would make sense to such a network as boats could easily arrive and depart at all times of day. Some refs: https://books.google.com/books?id=uQMMAQAAQBAJ&pg=PT38&lpg=PT38&dq=celts+shout+message+network&source=bl&ots=Z0AqU-JPr2&sig=YqK4rFHvQw5_3eLAeioFPeNQgYU&hl=en&sa=X&ved=0ahUKEwjol8yb-P7bAhVqllQKHc73BTkQ6AEINzAB#v=onepage&q=celts%20shout%20message%20network&f=false https://books.google.com/books?id=uQMMAQAAQBAJ&pg=PT38&lpg=P... https://www.forbes.com/sites/icoengine/2018/06/06/parkingo-innovating-mobility-via-the-blockchain/#11b58afa4d58 https://www.forbes.com/sites/icoengine/2018/06/06/parkingo-i... https://www.salon.com/2013/11/03/the_celts_were_smarter_than_we_think/ https://www.salon.com/2013/11/03/the_celts_were_smarter_than... https://www.theguardian.com/books/2013/oct/11/ancient-paths-graham-robb-review https://www.theguardian.com/books/2013/oct/11/ancient-paths-... https://www.thetimes.co.uk/article/the-ancient-paths-discovering-the-lost-map-of-celtic-europe-by-graham-robb-7cjzlqpl7wn https://www.thetimes.co.uk/article/the-ancient-paths-discove...