Following the little brook that emerges at what is possibly Indigenous made stone work shown in this previous post: http://wakinguponturtleisland.blogspot.com/2014/11/serpent-to-serpent-to-entrance-of.html, led me to several places where little stone bridges crossed the stream:
Looking east above, west below.
Looking east above, west below. There are hints that there are rows of stones buried beneath leaves and debris along the brook, but below you can see the distinct row of boulders and smaller cobbles as well, that run a long the stream but then veer off to meet an outcrop.
While there has been a culvert has been modernly added on the left, there is a tunnel the brook enters:
(The modern addition:)
To be continued...