I have watched each of the films and made tiny notes at crucial points in an attempt to draw a map of the Great Valley and the surrounding areas. I haven't yet uploaded a map, but I will draw a text description.

Lands Around GV:
N: Mountains
NE: Water from 3 (within Mts), Barren lands/Berry Valley.
E: Barren Lands from 1.
SE: Smoking Mountains.
S: Smoking Mounts and desert.
SW: Desert, then Land Of Mists)
W: Desert, and Movie 5 lands
NW: Mountain routes, and Movie 9 lands.
(That was written presuming the mountain chain runs N-S. Looking at maps, and judging by scenes in 1 and 4, the chain may really run NNW-SSE.)

Now follows my reasoning. (WARNING: LENGTHY NOTES FOLLOW) Please note, since some movies show areas that don’t necessarily fit together, I have changed a few things to fit them better. For example, Sun placement has not always been noted.

First of all, what we know from the first film is that the eastern lands are barren, the north and south are divided by a large chasm, and a large mountain chain runs north-south in the west. This is where the great valley is.

Now, lets look at the main dinosaurs, and where they were found. Personally, I think the GV was located in Western America, as an older feature of the Rocky Mountains. Look at this map:US Cretaceous Map
Taking some liberties with the surrounding areas, that could easily be the world of LBT.

Triceratops was only located in Western America. Apatosaurs, Stegosaurs and Pteranodons were also found here. Saurolophus was too, but the Asian species which had a longer crest fits Ducky's look better. However, there was a land bridge connecting Asia and America in the north, so her family could have migrated.

Now, lets look at the knowledge that we got in each film.

In the first film, we know that there are two mountain lines to the east. One is the barrier that stops Sharptooth following them. Behind this is the Longneck statue. Then, there is the other mountain line that Littlefoot pushes Cera down to fight in. Over the hill down there is the Great Valley. To the left (South) are "Mountains That Burn"; these are presumably the same as the Smoking Mountains. The tiny lake that they defeat sharptooth at is located near the GV (You can see the rock on the plateau over the lake when Littlefoot sees his mother in the clouds. The film originally had this scene earlier.) As for the Great Valley, one thing that must remain consistent, is that a waterfall flows into the valley, and a river runs from it, East To West.

The second film doesn't show much outside the valley, apart from the large area of tar and skeletons which appears to be the same place as the smoking mountains in the first film. As for the route that is taken to get there, it looks as if they followed Ozzy and Strut over the mountains surrounding the GV, travelling south towards the Smoking Mountains, before returning through the area created by the rockfall; a passage to the east.

The third film gives the waterfall a name; The Thundering Falls. When the trapped water is found, it takes up a large area (this may be flooded land). It must be near the falls, and the land to the southeast has been mapped, that means that the water must be to the northeast, probably further north than east, to provide room for the adults to reach the valley (In the first movie)

Four and Five are a bit confusing. Four shows the valley emerging from the mountain chain into a desert peppered with rocks. Across from these (Apparently West) are high rocks that border the Land Of Mists.

Five also shows a vast area of desert, although in some areas it appears to be desolate land. This could be east, but I doubt that the characters would ever return there, and also in Nine, Cera remarks that they went “Right” at the Smoking Mts. The explanation? The land is desolate, recently wrecked by the locusts.

Six shows the area where Saurus Rock is located. This is an interesting area. First of all, in Grandpa Longneck’s story, he claims that Saurus Rock, and the area where the attack took place, were a part of the Great Valley. If you ask me, it once was an area of the valley, but was abandoned for lack of safety, or a later event that made it unsafe, such as an earthquake. For a mountain line that big, plus with volcanos, the GV must be on a faultline (This could be the San Andreas Fault, following my Western America theory).

Seven is interesting as it shows that the GV is not completely bordered by mountains. The GOF cross a gorge over a river that divides the Valley and the Smoking Mountains, and Threehorn Peak. The river is seen to go over into fertile lands. Presumably, this area, and Threehorn Peak, are to the south, past the dangerous areas of the first film.

The flashback in their film is also interesting. Presumably, the great divide stretched all the way to the mountains, otherwise the families could have reunited easily. Pterano leads his group to a small canyon in the south (left) while the others continue their trek (right).

Eight shows that there is a mountain route to the valley. Since all other directions have already been shown, this must be a northern route. There is also a tall mountain that is apparently used as a landmark. This would make up part of the western wall of the GV.

Nine shows more waterfalls, but this is a result of the rains. Interestingly, an Earthquake destroys one small part of the Valley, creating a gorge. As for the route, Presumably, the GOF are travelling west with Mo.

Ten is interesting, as their route appears to go through the Land Of Mists. Both 4 and 10 go through a high rocky area, and then a misty swamp. The longneck herd in movie 10 go further. This places the LOM to the SW. Further south is the longneck canyon.

11 shows nothing new, just the same dead lands of the smoking mountains. Presumably, their cave is located to the SE.

12 is just a barren land, that could be many areas. Since they go past an active volcanic area, it is probably south, or possibly the area created by the earthquake in 9.

13 is interesting. The land we see when they first enter the mysterious beyond doesn’t match any of the sequels yet, so it must be the lands to the north of the divide. Berry Valley is located far to the north, though slightly to the east of the GV.

Okay, that’s enough for now. I have more, but it can be difficult adapting my notes to computer form. I’ll post more later.

Oh yeah, and I forgot to add:

The time I think the GV is in is not near the extinction point. Note, the end of the first film has the narrator state that "Generations upon Generations" passed down the stories of their ancestors. Since some species would have been extinct at different times, we can assume that the movies take place during a fictional time, such as Mid-Late Cretaceous.

Another thing is that whatever the time is, the land is going through some changes, as evidenced in movies 1, 4, 8, and 9. This could explain the change in some lands.

Something else of note is that Grandpa Longneck claims to have lived in the valley as a hatchling in 6. We see that he knows what locusts are, so maybe they decimated the valley years ago, and he left to the east. There is nothing that says that the Great Valley was always known by that name.

Also, in his story, there is a focus on Longnecks. This could reflect the segregation that would have been rampant in his youth, or it could mean that the valley was once home to Longnecks. The latter seems unlikely, as there is a Threehorn and a Bigmouth visible, plus Thicknose, the oldest inhabitant, remembered multiple herds in the valley. This raises the question of whether or not Grandpa Longneck and him knew eachother. Of course, they could have lived at opposite ends of the valley (Come to think of it, were there any Longnecks in his flashback?)

Thanks!

A very thorough and methodically detailed analysis, Almaron. It’s inspired me to share my own attempts at pinpointing the locations of various LBT landmarks. Some disclaimers of my own before I begin: Firstly, many of my observations and opinions conflict with those you have shared, so please excuse me if my comments bear the slightest indication of rudeness; I assure you that I did not intend them to. Secondly, rather than being based on notes I have written down, most of these details I am recalling from memory. Thirdly, it is entirely possible that I have overlooked some details which may potentially nullify my assertions. If this turns out to be the case, bring on the humble pie. And finally, it should go without saying that the disparities between my interpretations and yours (or anybody’s, for that matter) can only be expected, as much of the LBT world’s pre-established geography is almost certainly not taken into account by the filmmakers whenever a new movie is made. That said, please forgive me for the amount of nitpicking in this post:

As for the Great Valley, one thing that must remain consistent, is that a waterfall flows into the valley, and a river runs from it, East To West.

Curiously, the valley appears to be fed by TWO waterfalls; one from the east where the gang first enters it, and another at the far end in the west. (I interpreted the latter to be the Thundering Falls, as the gang did not pass the vast mountain reservoirs seen in LBT III, and the falls they came across looked a lot smaller.) Clearly the Great Valley must absorb water like a sponge (maybe that’s why it dried up so fast in LBT III ), or else it had some sort of drainage system even before the topography-rearranging events of movie IX; otherwise it would be known as the Great Lake.

The second film doesn't show much outside the valley, apart from the large area of tar and skeletons which appears to be the same place as the smoking mountains in the first film.

I don’t think the location in the Mysterious Beyond seen in LBT II is a tar pit; probably just a stagnant pool of water situated over a volcanic vent (explaining the bubbles). I doubt the snake/lizard/aigialosaur-like creature briefly seen swimming through it could have so easily done so if it were tar. The skeletons seen there could have belonged to dinosaurs that simply didn’t make it to the Great Valley as a result of starvation or being ambushed by sharpteeth, or even succumbed to an eruption of volcanic fumes (a creepy thought... :unsure). My point being, I don’t think this is near the tar pits from the first movie. It still could be near where the gang entered the valley, though (i.e., in the east): Ducky’s family’s nest is shown as being relatively close by (Ducky was the first member of the gang to reunite with her family), and it’s conceivable that the migrating herds entered the valley from the same direction, sealing the opening behind them so that sharpteeth couldn’t follow. (Admittedly, my reasoning here is largely conjectural.)

The Smoking Mountain, seen in movie II and referenced in III, is presumably in the west, as Grandma Longneck states that the sun will touch it when it is the longnecks’ turn for water, and at the time it already appears to be too late in the day for the sun to have not touched it yet on its morning ascent into the sky.

If my assumption that the Thundering Falls is located at the west end of the valley is correct, then the parts of the Mysterious Beyond seen in LBT III must also be in that direction. My belief is that it is northwest (the ledge from which the gang first discovers that the water is blocked being in the north).

Five also shows a vast area of desert, although in some areas it appears to be desolate land. This could be east, but I doubt that the characters would ever return there, and also in Nine, Cera remarks that they went “Right” at the Smoking Mts. The explanation? The land is desolate, recently wrecked by the locusts.

Locusts don’t eat wood; only the soft parts of plants. I think that that place really was a desert, and that the dinosaurs were simply forced to pass through it in their search for a new home. However, I agree with you in that the locations seen in movie V are probably either west or southwest of the Great Valley.

Ten is interesting, as their route appears to go through the Land Of Mists. Both 4 and 10 go through a high rocky area, and then a misty swamp. The longneck herd in movie 10 go further. This places the LOM to the SW. Further south is the longneck canyon.

I personally doubt that the swamp in LBT X is the Land of Mists; probably just a similar-looking region. Same goes for the rocky area.

Something else of note is that Grandpa Longneck claims to have lived in the valley as a hatchling in 6. We see that he knows what locusts are, so maybe they decimated the valley years ago, and he left to the east. There is nothing that says that the Great Valley was always known by that name.

Unless you're thinking of a different line (in which case I’m missing something ), what he actually said was that his own grandfather had told him stories about Saurus Rock. That could mean that one of Grandpa Longneck's ancestors lived in the Great Valley, but not necessarily him. It's even possible that his grandfather or grandfather's ancestor had heard about Saurus Rock from other longnecks who had been to the Great Valley or heard the story themselves from OTHER longnecks that had been there. Inherited stories appear to be a cultural characteristic of longnecks, and indeed all dinosaurs in LBT (obviously, considering they have no other means of passing on information besides word of mouth ).

That’s about all I’ve got for now.

Here's one of my most recent maps:

Great Valley Map

I know I have more explanations about the placement of things which I haven't posted, but I can't remember them at the moment. I'll post them later.

Remember, this map was drawn assuming that the LBT world takes place in Western US in the Cretaceous. Mainly because each of the GOF were found there (And only there, I think). So some things have been changed to make them fit better. Also remember, the scale is completely wrong. I just drew it that way to make it easier to draw. Chances are, there are miles of empty mountains inbetween some areas.

(Just remembered one of my explanations!) Raptors are rarely seen in the LBT films. In 3, they terrorize the water areas, and in 7, they attack Pterano's group, who went south, while travelling west (to the valley) on the northern half of the divide. Presumably, Raptors live in the NE areas of the lands surrounding the valley. (in 11, two raptors are seen in the smoking mts area, but they could be strays. Actually, they reminded me of the two raptors from the series. Which I haven't actually seen, only read about)

Whoa, I don't think I've ever noticed that second shot of the falls! It seems like an odd angle, but yeah, I think it is still the Thundering Falls (There only ever seems to be the one waterfall in the films, except for the ones in the newer films).

This is a good thread, and I await your observations!

EDIT: I forgot to mention, in an earlier map I noted a place as being two boulder pass, but now I find I can't remember where that is, or what movie it's from. Anyone know?

ANOTHER EDIT: Something else is, I often disregard differences in locations between sequels (has the valley ever been depicted consistently? Mountain and river placement change constantly). As such, I placed the Land of mists in a place that meant it could be the land travelled through in 10. That, and I couldn't find anyother place to place that land in 10. I also assume that forest from the end of 13 is the forest from 6 for two reasons. One, we haven't seen any other trees like that before, except in that valley. Two, following my map/observances, they travelled north, also where I placed the Saurus Rock area. This would indeed make it a shortcut, like Littlefoot said. In fact, since their parents found them there, maybe that's the entrance that they used to get to the valley in the first place.

As for justifying my ignoring of sun placement in some scenes, sometimes it just doesn't fit with what we know to be true about the LBT world. Although, sometimes the sun appears to be in a different area depending on where you are. (At least, it seemed like that one time to me. I could be completely wrong here.)

This is a map I drew in the Fanart section... I'm pretty sure it went unnoticed during the lull of the summer.

EDIT: There are lots of places on their I made up names for such as:

Big Water:  The Great Sea
The place where they stay briefly in 5: The Dawn Valley

Since its for my story, I had to make some guesses and suppositions.

^ Perhaps the spiketails headed north because their typical migratory patterns involved them traveling south to the Great Valley during the cold times, and returning north when things warmed up. Therefore, they were familiar with the areas north of the Great Valley (it was only the blizzard that threw them off course), and assumed that they would be able to find another location where there was food, or, failing that, circle around the valley from the northeast or northwest in search of greener pastures further south. It’s a shaky theory, I’ll admit; it seems strange that they did not simply take a more southerly route out of the valley, but it’s the best I could come up with.

The Thundering Falls of LBT 3 looked very different though from the falls Littlefoot stood beside when he entered the Great Valley in the original movie or from the falls Littlefoot's grandparents used to take a "shower" in LBT 4.

That’s another reason I assumed the Thundering Falls were different from the waterfall seen at the entrance to the Great Valley in the first movie; they looked too massive to have flowed from the relatively narrow river Littlefoot is shown standing next to, and their banks above the Great Valley, as shown in the third movie, were not so rocky. Still, from the looks of it, the first movie waterfall is apparently the source of the valley’s main river; therefore I think now that the Thundering Falls were intended to be the same, and am willing to attribute the discrepancies to inattention to detail on the animators’ part.

As for the waterfall in the middle of the Great Valley (the one seen in LBT XII), I had considered that perhaps it was formed as a result of the earthshake in movie IX. I have also considered that it is the same waterfall that appeared in the TV episode “The Great Log-Running Game”, referred to as “Roaring Falls”.

I also think the “New Water” of movie IX is probably in the west of the valley (where I previously assumed the Thundering Falls to be ), and the river that the gang follows to get to the Big Water may be the source of the fresh water in the coastal oasis the adult dinosaurs find in movie V.

^ Right, layout designer. Pardon me; I didn't know the terminology.

Actually, it's the fault of whoever TOLD the layout designer to design the backgrounds that way. :

Yep, I agree with you on those theories Pangaea. I thought that could be why they went north.

Regarding the divide/waterfall, in an older version of this map, I assumed there must be a fault line running SW-NE, to explain the divide in the first film, and I assumed that it travelled through the valley, and that's what caused the quake in 9. (Back when I started mapping the areas, I used a map in the Fan Art section as a vague basis, changing placement of things when I found new evidence. I don't know where that is now, but if anyone can find it and link to it, it could be interesting (I believe Malte uploaded it, but didn't draw it; a friend did), despite the odd error, and lack of labelled places.)

I had another look at Caustizer's map, and if you flip it upside down, it's quite similar to mine, in terms of placement of the canon locations. We must be close to figuring out where everything is and making a final map! Can someone make a list of locations of the places in the TV series, and where they are in relationship to known landmarks(i.e, waterfalls, the sun, other)? Then we could make it even more accurate!

EDIT: I also think that there needs to be another route to the valley from the NE. We know that the divide went to the cliff wall (13, plus they didn't reunite in 1), and no adult footprints were found in the first film, so they took a different route into the valley. This could be where the water (3) is, as the area is flooded, although it could be through the Saurus Rock valley, as that appears to be a good entrance route, plus it resembles the exit route taken by the grandparents in 13 (Since they were following their kids into the lands they came from, it would make sense to return the way they came, unless they knew of a quicker route, which is unlikely, as they haven't exactly travelled there before). We also need to mark the small valley near the valley, the divide, and the water, which Pterano led many to (7. With it being this close, he may have assumed this to be their safe place).