Earthworks Across the Licking Valley

On Facebook a couple of days ago, Jeff Gill of the Newark Earthworks Center (among other things!) praised some of the LiDAR images I had created that were related to the earthworks around Newark.

But he asked for a “nudge”.

The image in question appeared in my blog entry Salisbury Hill — Follow the LiDAR (Part 1). It’s a LiDAR topographic image I produced that covers about a 12 mile by 8 mile section of the Licking River valley around Newark, with some of the major earthworks overlaid onto it. Here’s the image:

A LiDAR View of the Newark Area

[You will want to click on it for the full 2400×1600 pixel version.]

While Jeff really liked the image (he had just visited Salisbury Hill), here’s what he said:

I’d nudge that northern avenue up a few degrees to point due east, and it would then also line up with the visible notch on the bluff, the “Eastern Gateway” so-called. But your LiDAR master valley view inspired me today!

What’s he talking about? He’s talking about that purple line that runs just slightly south of east. That’s assuredly not quite right. Here’s the story.

When I made that image, I overlaid the 1862 Salisbury Map onto the LiDAR.

The 1862 Salisbury Map of the Newark Earthworks (click for larger version)

The Salisbury Map shows the earthworks at that time, and shows that “Eastern Gateway” ending at a notch in a bluff above the Licking River. In making the composite, all I did was resize and rotate the Salisbury Map so that the Great Circle (easily visible on LiDAR) and the Observatory Circle of the Octagon (also easily visible on LiDAR) lined up. The image above is the result of that, with the still-existing mounds in black, and the missing ones in purple.

However, in A Walk with the Currents, Jeff had established the location of the notch for the Eastern Gateway. In fact, I’d LiDARed it.

LiDAR Image Showing the Notch

So what went wrong? I suspect that Salisbury just wasn’t super-accurate over long distances, and he was more wrong east/west than north/south. What I have now done is reworked that map while using patches of the Salisbury map to align on more features.

First, here’s a 1200×800 pixel image of the major earthworks area (click as needed). The Octagon and Great Circle show up very nicely.

LiDAR Image of Newark Earthworks

[Note that I’ve compressed the elevation-shading compared to the first image so that the mounds show up. That means the colors have different designations than in that image.]

This next image shows my overlay patches.

Salisbury Map Overlaid in Patches

For the first one, I aligned with the Octagon and the Eastern Gateway. (The relative size isn’t quite right; while the railroad matches, the size of the Observatory Circle doesn’t. However, fixing that makes only a small change—I checked it.) Another patch aligns on the Great Circle, the railroad and Oval, and the Southeast Gateway aligned on Shawnee Street, where we figure there was another notch through a bluff. There’s another patch to connect the Octagon and Great Circle (which was all messed up due to distance). And there’s a final patch to get that square earthwork downstream on the Licking.

When you put it all together, you get this 1200×800 pixel image of the major earthworks in the Licking Valley.

Reconstructed Earthworks on the LiDAR

Now all I had to do was put that onto the full image of the Licking valley area. But while I was at it, I thought I’d add two more mounds that are in that 12×8 mile area. First, I wanted to see where the Alligator Mound sits.

The Alligator Mound (assuredly not an alligator, but maybe the Underwater Panther) also shows up on LiDAR. Here’s a compound image with the LiDAR mapping and the Squier and Davis line drawing.

Locating Alligator Mound

You ought to be able to see the slight color variation from the mound.

I also added the earthwork on the top of Salisbury Hill.

So, here’s the money shot.

Licking/Raccoon Valleys Showing Earthworks Over LiDAR

It’s a 2400×1600 pixel image (just like the top image), but with everything aligned. (It also has more neatly-drawn earthworks.) You definitely want to click to see the full version.

The Alligator Mound barely shows up on the western side up Raccoon Valley. The Salisbury Hill earthwork shows up fairly nicely.

And then I noticed something that I’d never noticed before.

The Alligator Mound and Salisbury Hill have direct views of each other across the South Branch of the Licking and up Raccoon, illustrated here.

Across the Valleys

[Don’t bother clicking—it’s a small image.]

Now, my understanding is that Salisbury Hill is Hopewell and Alligator Mound is Fort Ancient, so they supposedly are not contemporaneous. But it does strike me as quite interesting that these two high points with such an orientation both have mounds on them.

These days, Salisbury Hill has a lot of trees on it. Even with the trees one can get a pretty spectacular view across the Licking/Raccoon Valley, but I bet the Native Americans kept the hilltop free of trees, or at least free on the northwest side to be able to look out on the valley and towards where Alligator Mound is located. (I can speculate that during Hopewell times there might have been something there that was later overbuilt by the Fort Ancient culture.) I’m not usually a fan of cutting down trees, but this is one location that I would seriously consider as a good spot to do so.

Anyways, there’s the new and improved Licking Valley earthworks image.