some rambles & fun facts about the beach in project hail mary
if you're wondering what & where it is before i start yapping, it's durdle door, in dorset
some background context, my first exposure to project hail mary was when folks started freaking out on the local facebook groups - ryan gosling's coming to town for filming a new movie!! i thought to myself ahhh fuck. the city that i go to uni at is gonna cameo in a gosling film. fml i guess i have to see this now
anyways i forget about it for ages until the movie drops and i finally go see it and imagine my surprise when i'm expecting miserable fuckass portsmouth and instead. i snap upright like-
"is that durdle door?!" "yes i think so-" "the dorset fieldtrip?!" "yep" "ohh my god. they went there?!" "i guess so" "what the fuck" <- live reaction of me and my bf who both have done fieldwork there related to our respective degrees (geology & palaeontology)
anyways now for some fun facts:
the arch structure you see is part of portland limestone formation, and is going to eventually to erode away entirely
the arch itself it estimated to collapse anytime from 100 years time, to several hundred years time - depending on ongoing weathering/changes in weather patterns (woo yay climate change)
the cliffs are mainly cretaceous era chalks, and this area is so prone to landslides it's not even funny. we went for a day and literally i think the week after? there was a landslide
fun extra fact about the chalk, they contain loads of coccoliths which are great for dating rocks + analysing the palaeoclimate during deposition
whilst the directors cut implies the reason behind the beach being shingle is because the eridians can't figure out sand particle size, the reason why the beach is flint is literally because of geology; it's been eroded out of the cliffs
sidenote it would be much nicer if it was a sandy beach but unfortunately that wouldn't make much sense geologically
at the very end of the movie, we see some beds extending into the water and the camera panning out as he begins teaching the little eridians - this is in man o' war cove is is on the other side of the archway!
this is visualised in the little diagram i made at the very start of the post, so ryland's house sits atop where the pathway down IRL is located, and the beach where he and rocky sit on is the western side, and the classroom is on the eastern side
the line in the movie where ryland says "the beach is always changing. you could go to the same spot every day. you're always looking at a different beach." is so especially true because durdle door is (like i said before) constantly changing both from erosion, landslides, and just the result of it being a tourist location
it's been different everytime i've been, in fact it was closed? earlier this year because the paths were badly damaged from storms
so it's like the paths you see in the film are the old ones, and if you visited, they'd look different/they'd be new
sidenote not confirmed at all but i wonder if they chose durdle door because of its "proximity" to portsmouth because of filming locations in hampshire... it's a 2hr drive but ig that's not far if you've got a film crew
anyways here's some pictures from when i went for fieldwork a few years ago:
--edit 07/05/2026 some more facts that my bf said i should add!--
durdle door's eastern cliff face, the one adjacent to the eridian classroom, is specifically purbeck (Purbeck) limestone and features some awesome preserved wave ripples
kinda like the ones you'd see on a sandy beach, except they're from the late jurassic-early cretaceous
the beds i spoke about in the last post, the one that ryland/the eridian classroom is situated on, is the cinder bed - which is a mass mortality shell bed, and we have a cobble of it*:
the thin part of durdle door, where ryland grace's house + tree are, is the wealden (Wealden) group, which is composed terrastrial sandstones that represented a period of sea level regression :)
the wealden group is characterised as a freshwater (no ocean) fluvial (rivers) floodplain, so lots of water stuffs!
oh also the wealden group has small deposits of limonite which is a neat yellow mineral that derives from iron (the whole wealden group is quite ferric)
sidenote it'd be sooo cool if people drew the eridians with textures like the local geology (maybe i should do this... but this is all chalk and limestone soo they'd kinda just be grey. interesting textures tho!)
*durdle door is a sssi (site of specific scientific interest, protected by law) we did NOT hammer a chunk of it off, it is illegal to take pebbles or samples from a sssi without explicit permission :(
so yea! hope someone enjoys reading this mini info-dump about the beach. super recommend people visit, it's a beautiful place and a great way to spend a day. the beaches are fantastic, the geology is great, and you might even see an adder!
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