Yes, that is so true...
What they did do, was to be aware, & know all about that...
So what could, and Did they do about it, in case on the
day that they, or someone else, that was 'in the know',
with all of the proper training and experience, happened
to return to the Treasure/Mine site, on a cloudy day?...
They set up rocks in more than one spot, in the immediate
area, and carved multiple carvings of the same, or closely similar
objects, to be interpreted, by 'The Initiated'... Some of those carvings
did not require a sun shadow, to be seen, even though they may even
be hidden, right in plain sight. Oh, yeah, they would likely be greatly
enhanced, if the shading were present. Some would disappear, and
some show in a limited window, as has been discussed. Here's the
thing. Even multiple carvings, may go unnoticed, a little while, or,
maybe even forever... Unseen, by Avid Deer hunters, for example.
Who are skilled and experienced, in Tracking Deer tracks, big Cats,
Elk, Moose, Caribou, Wild Hogs, Turkey, etc., etc. ... But, those same
very experienced hunters, don't necessarily know a carved, man shaped
rock or rocks, even if it is staring at them right in the face... And that is
just how good they, the carvers/workers/monument builders were...
The easy key to seeing, what even the trained and experienced eye, may not
even pick up at first, for who knows how long... Is to take pictures. Lots of angles,
distances, lighting, oh did I say angles... Yes it is much better, the brighter the sun,
and easier to see what was done, so to speak... But once you have really studied,
and have gone back over and over, your pictures on your screen, and looked at
the rocks at the location. If it IS a highly marked area, not just a marker along
the trail, you will begin to see there is something(s) there. Your camera
just makes it so easy for you, (as I learned from people talking here on
TN) by compressing the shadows/images. Then, when you take all of
that compressed Info, so to speak, and enlarge it, it becomes so
much easier to see. If you have been or ever are in a highly
carved area, you will not believe what you have often walked
right past, when you do the pics, even seeing things later,
that you had initially missed, knowing what to look for...

...Besides the real dark shadowing of the sun, just the dim
shading of daylight, will look possibly like something, to the naked
eye, in some cases... Then, your cameras' picture taking abilities,
will reveal more... Yes, there is always likely much more, to
be seen, in the light/reflections/shadows/contrasts,
of our ingenious, sometimes secretive sun...
I will try to get together, and present a little example, Amigo...
...Crosse