Exhuming my thesis, part IV

 This follows on my previous post here of a series started here. 

A case of "AI to the rescue", it's listed on my blog's pinned post under 2026. 

In my initial post of this series, I wrote (caps added):

That prompted me now to look up geophysical data (aeromagnetic anomalies, Wikipedia): will it allow to GLIMPSE terranes in the subsurface below the Great Lakes, as well as earlier Archean and later Phanerozoic features such as, respectively, the Wawa Lineament and the Niagara Escarpment? Lo-and-behold, I found aeromagnetic data (NOAA) and sketch-mapped them below on my desktop GIS (Esri)!

Was "glimpse" a subconscious play on words with GLIMPCE? A scant half decade after my thesis, it was a deep seismic refraction program to image the Mid-continent Rift underlying the Great Lakes (Perplexity). It followed earlier similar imaging the Grenville Front Tectonic Zone (Perplexity). That much I knew, tho not in time for my thesis early eighties of Geol. Surv. Canada work mid eighties

Imagine my surprise when the prompt "deep seismic survey Manitoulin Island Discontinuity under Lake Huron &/or Lake Michigan" in Perplexity yielded this:

The Manitoulin Island Discontinuity (MID) is a significant geological feature identified in deep seismic surveys beneath Lake Huron near Manitoulin Island. These surveys, part of the GLIMPCE project in the late 1980s, imaged crustal structures across Lakes Superior, Michigan, and Huron, including the MID labeled in seismic line maps.[prd-0420-geoontario-0000-blob-cge0eud7azhvfsf7.z01.azurefd]​

GLIMPCE Seismic Surveys

GLIMPCE conducted multichannel seismic reflection and long-offset refraction surveys, collecting 1350 km of data along eight profiles, including lines in Lake Huron near Manitoulin Island. These deep surveys targeted structures like the early Proterozoic Huronian continental margin and middle Proterozoic Grenville front, with the MID marked as a key feature in the vicinity. High-resolution data revealed crustal velocities, rift basins, and Moho depths up to 55 km, though specific MID details relate to broader tectonic boundaries.[download-telecharger.services.geo]​

Geological Significance

The MID appears in regional cross-sections as a fault or boundary along the southern margin of the Superior Province adjacent to Lake Huron, influencing Huronian megacycle sediment accumulation. Magnetotelluric surveys along GLIMPCE line J on Manitoulin Island and Bruce Peninsula detected conductive black shales masking the Grenville Front, limiting resolution of underlying structures. No direct evidence links it to Lake Michigan surveys, but GLIMPCE profiles extended through that basin.[ovid +3]​

Related Studies

Shallow acoustic surveys on the Alpena-Amberley ridge under Lake Huron identified Paleoindian hunting structures but did not probe deep discontinuities like the MID. Recent 3D seismic work near Lake Huron focused on nuclear repository sites, not the MID specifically. For GIS or mapping applications, GLIMPCE data integrates with potential field anomalies for midcontinent rift modeling.[pnas +3]

Please go here to get the full text incl. list of references. In the "+3", my thesis paper was mis-attributed, and I contacted academia.edu to correct it. I add here the front page of the original paper [usgs].

click to enlarge, original here

This closes my series... thanks for reading!

​

Richard Cœur de Lion's return trip

This follows on from new maps posted on history & newmaps.

Medievalist.net posted here a rethink of the circumstances of Lionheart's return from the Third Crusade, summary here and in three-sentences:

The article presents Attila Bárány’s argument that Richard I’s capture after the Third Crusade was primarily a product of high politics, not an accident of storms, pride, or divine punishment. Richard’s secretive, indirect route home and his decision to pass through risky territories are treated as calculated responses to the political threats posed by figures like Philip Augustus and Emperor Henry VI, who could profit from his detention. Leopold V’s personal resentment is seen as a catalyst rather than a sufficient cause, with Richard’s captivity and ransom functioning as tools of imperial strategy and diplomatic theatre.

Even more maps, with a twist

In this opening view from this video here, doesn't the Grand Canyon appear inverted to you? As in the deep parts pop up instead of down!

click to enlarge 

"All you have to do is ask AI", sometimes

 Let's follow on this post here about more intriguing geomorphology (land forms underpinned by geology), with a little help from AI in the first instance.

Hungary 

LinkedIn @markku-ylisirniö posted here a cool map of Hungary:

screen grab from original post, click to enlarge 

East Anglia environment in a global context

 This follows on blogposts about East Anglia in general here. The last post on infrastructure affected by sea level rise is here. Contrast below Environment England's Risk of flooding from river and from sea at left for waters coming naturalls from onshore & offsore, and my Seal level rise model by simply intersecting various sea level elevations and Ordnance Survey topogaphy (intro here and workshop here). Think of it below as fresh water largely going NE to the North Sea at left, and at right as sea water encroaching largely SW onto the land:

A Roman Holiday

This follows on a map story here. Next history map is here.

Update : check out below how a new map, itiner-e, updated the Roman Roads view.

Update 2: speaking of malaria in second map, appended maps on trade routes that triggered the Black Plague in the 14th c. Mediterranean.

Not William Wilder's 1953 Gregory Peck & Audrey Hepburn flick (Wikipedia)! When drawing up a map of Apostolic Palestine for local Catholics, I ran across Ancient World Mapping Center (AWMC) at UNC-Chapel Hill. While their web app (ArcGIS Online) is a cool one-stop-shop for their rich data set - for ex. I cannot do point clustering (Comet Assistant) with my standard Argis Pro desktop license -  I loaded, picked apart an re-sorted some of their data for some interesting insights. 

AI to recreate a lost picture

This follows on AI "lessons-learned, lessons shared", last post here and master post here.

Here is another use of Google Gemini AI. A LinkedIn discussion here described fog/cloud banks in Cen. & Nor. Cal. against nearby ridges.  I commented on same viz. Yucaipa Valley & Ridge in So. Cal. Here is my comment:

How to build AI Agents

This follows on my AI "lessons-learned,  lessons-shared" mainly on my Ongoing Crash Course pinned atop this blog, that links all items on my various socials.

Maryam Maradi (LinkedIn) shared on-going how-to's I pay-forward here to the rest of the world. I posted the texts on the links below her excellent posters also in-text (click to enlarge). My (liked) comment on her second post was:

This is so excellent! I'm a geologist & GIS-er of 40-odd yrs., w interest in geophysics in general & seismic in particular. I have never seen such a comprehensive review and sign of hope for disaster response... Thanks!

Samurai in early 1600s Spain!

This follows on from a map story here. A follow-up is here.

Update: fascinating twist in failed outreach by Elizabeth I to China below.

Update 2: mid-19th c. 2nd mission to France mapped the same way @ bottom.

I thought that So. Cal. Spanish missions were early (mid-18th c.)... well here's an earlier story of intrepid early diplomats & missionaries - not seasoned sailors as Longest tall ships routes here - after long-distance missionaries of the Apostolic Levant here. Perplexity opens here as:

More map art, Part II

This follows on a map story here. The next one is here. 

The original "More map art" is  here: a world map in Natural Earth projection with Mean Annual Climate Temperatures and Natural Earth countries.

Equal Earth vs. Spilhaus projection, masking onshore areas

The original post starts as "a few years ago I used Charlie Frye's online lesson Explore future climate projections to learn how to use NetCDF and map temperature regimes - it's shown below in Patterson & Savaric's Equal Earth Projection..."