"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 

I commented on his post: 

This is fascinating! I wonder what those striations / lineaments are in the W part of the country? Glacial followed by river erosion along the edge of Quaternary ice sheets, or structural features from underlying strata (tho I don't recall any mountain-building nearby). Must look up geomorphology & geology. Thx!

My late Hungarian geologist dad could have answered this RIP. He had a relief map in my bro's old room I'm currently using (long story):

author photo, click to enlarge

Hence my answer to my comment on LinkedIn:

The geological map shows strata lying EW, so those are likely geomorphology as in glacial or fluvial erosion, to be continued...

 So I ask Perplexity AI (prompt in AI-speak):

reason for geomorphology NS striations in West of green topo map, when geology formations in coloured map run EW

And it obligingly answers before I can blink:

The north–south “striations” in the western part of the green topographic map are mainly erosional and structural lineaments (valleys, ridges and scarps) that follow younger fault and drainage directions, whereas most of the coloured geological units represent the older, regionally east–west–trending stratigraphy. [1][2]

Geological grain vs. relief grain  

- In western and southwestern Transdanubia the pre‑Neogene basement and many mapped formations trend broadly east–west or ENE–WSW, reflecting the main Alpine–Carpathian structural grain shown on the geological map. [1]

- The topography, however, is shaped largely in Neogene–Quaternary cover (Pannonian sediments, loess, fluvial deposits), which can be incised independently of the strike of the underlying units, so relief need not parallel the mapped formation boundaries. [2]

Role of faults and block tilting  

- The Transdanubian region is dissected by numerous neotectonic faults whose dominant strikes are ENE–WSW and NNW–SSE; differential vertical movements along these faults have tilted blocks and guided valley orientation. [3]

- In the Transdanubian Hills specifically, the western sector is described as having parallel ridges and “meridional (north to south) valleys”, with additional valleys aligned along NNW–SSE fault lines, exactly the kind of lineated pattern visible on the shaded‑relief map. [2]

Drainage and erosional control  

- Major rivers and smaller tributaries in the Pannonian Basin commonly adjust their courses to active or reactivated faults; changes in sinuosity and straight reaches coincide with structural lines, reinforcing north–south to NNE–SSW drainage where these faults exist. [4][3]

- Over time, fluvial incision along these structurally controlled channels produces elongated valleys and interfluves that appear as north–south striations in shaded relief, even though the bedrock formations themselves may strike mainly east–west. [5][2]

Local explanation for the western striations  

- In the western Transdanubian Hills between the Alpokalja and Lake Balaton, Quaternary gravels, sands and loess overlying Pannonian clays are cut by such meridional valleys, giving the green topographic map its prominent N–S striping. [2]

- The coloured geological map emphasizes lithostratigraphic boundaries (largely E–W) rather than the neotectonic fault pattern and erosional valleys, so the apparent mismatch arises from comparing an older structural grain with a younger, fault‑ and drainage‑controlled geomorphology. [6][1]

Citations:

[1] Geology 

[2] 1000028819.jpg 

[3] Geological deformations in the Pannonian Basin during the ... 

[4] A systematic overview of the coincidences of river sinuosity ... 

[5] Geomorphological regions of Hungary (1970) 

[6] Explanatory notes to the Geological map of Hungary, 1:500 ... 

[7] 1000028817.jpg 

[8] A geomorphic evolution of the Transdanubian Mountains ... 

[9] Wind erosion under cold climate: A Pleistocene periglacial ... 

[10] Geohazards of the natural protected areas in Southern ... 

[11] 1_Hungary in Map.indd 

[12] Geology of Hungary - Wikipedia 

Great Lakes 

 Likewise @heididaulton posted here an intriguing story about perils of shipping iron ore in the Great Lakes exactly 50 yrs. ago. It had a map of the bottom of Lake Superior, also with NS submarine erosion to the EW geologic fabric of the Canadian Shield it sits on. 

screen grab from original video, click to enlarge

I posted here my thesis area to the E of this. You can see below that the submarine erosion guillies coincide roughly with the arc of the Great Lakes Tectonic zone. It's a pre-Cambrian intra-cratonic volcanic rift system more prone to erosion that the granitic Archean... that's called a shield for a reason! Indeed the Great Lakes were formed after the retreat of the N American inlandsis (continental ice sheet) by a combination of that erosional weak point, as well as the edge of the post-Cambrian limestones laying flat on top southward and ending northward along the Niagara Escarpment (Wikipedia). I combined below the basement map in pastels from a previous blog post here, with the Niagara Escarpment in red from Wikipedia (having found no inclusive CAN - US map of same, I overlaid them graphically as they were in similar projections):

QGIS map by author, click to enlarge

You see clearly that not only do the submarine canyons, but also the significant relief below Lake Superior pointed out by @heididaulton, coincide with the arc of the Great Lakes Tectonic Zone in olive: it separates relatively less rugged areas of the Canadian Shield (pre-Cambrian) in grey to the N, inside the other arc of the Niagara Escarpment (post-Cambrian) in red to the S & E, and the Penokean Orogen in purple to the S & W.

Note that the latter includes the Iron Ranges, not only of mining importance opening this section, but also the start of life as we know it per edX MITx on early Paleobiology here.

Another intriguing wrinkle: enlarge the map and see the EW lineament left of the word Mazatzal Terrane at lower right; that may reflect the Manitoulin Island Dicontinuity referred to earlier here.

 ... Same as Bay of Biscay canyons explained here, no AI is needed to sort this one out!

from original post, click to enlarge