As a might have been geologist, I really loved the Middle Earth blogs. It's a shame so many of the comments on the original host site are "why are you taking this seriously, it's a fantasy map" are missing the point that the critique itself is obviously also a bit of fun from a fan, and I think very fair in weighing up the context that a) Tolkien was a linguist, not a geologist, b) even if he had been a geologist, plate tectonics wasn't overwhelmingly accepted during his lifetime, and c) the map is a part the narrative itself and may be as geographically reliable as the historical maps travellers compiled decades after the fact.
Neither Bilbo or Frodo were trained surveyors after all, and only saw transects of the world on their travels. When you walk long distances on foot your perspective is very different to how you would perceive floating down a river, or even passively riding on horseback. That's how I'd rationalise it anyway - its a map, not a world.
The Anduin I can actually accept as a rift or long parallel valley between the Misty Mountains and a much gentler range of hills to the east (unmapped, because the Hobbits barely travelled there). Likewise the mountains at right angles - well not all in one go, but given several phases of mountain building and rifting, and you only have to look at the topography of Europe and squint.
Mirkwood as a vast forest, and coastal Middle Earth as a mostly bare plain seems more questionable, given either westerly prevailing wind assumptions or the rich agriculture of the Shire being in the rain shadow. But again waive that as "bits Bilbo visited vs bits Merry and Pippin only glimpsed from the gap of Rohan while smoking some of Saruman's best shit".
Maybe "realistic fantasy maps" are missing the point, but I find the thought exercises of plausible geographies as fascinating as those of plausible histories.
Planetocopia did some fantastic stuff on those lines.