What's the difference between the Lance fm and the Hell Creek fm?

[Nanotyrannus35]

So what is the difference between the lance fm and the hell creek fm? They both have the same dinosaur species and from what I can tell, other vertebrate species. The only difference that I can think of is that the lance fm is in Wyoming while the hell creek fm is in South Dakota, Montana, and North Dakota.

[Troodon]

The Hell Creek Formation is indeed exposed in Montana, North Dakota, and South Dakota. Equivalent and contiguous strata in Wyoming are known as the Lance Formation and in Canada as the Frenchman and Scollard Formations.  These formstions share much of the fauna and are primarily identified by geographic boundaries with some minor exception but their depositions are a bit different in age and type of deposits depending on where they were located on the western inland seaway.

 

[jpc]

Indeed, as Troodon mentioned, they are basically the same.  And when you get to Colorado it is called the Laramie Fm.  The Lance tends to have more big sandstone bodies than the Hell Creek.  The Lance also tends to have better skin preservation than the Hell Creek and therefore more 'mummies' come from the Lance... almost always associated with these sandstones.  Additionally (although this is geographic, not geologic) there is a ton more Hell Creek outcrops than Lance.  I have also found that preservation tends to be better on the Montana side of the border, which makes me sad.   

Edited January 4, 2022 by jpc

[kgbudge]

Geologists sometimes joke about "boundary faults" where formation names abruptly change across a state boundary due to different state geological surveys sticking with different names. This sometimes leads to some pretty heated arguments (see page 37 here.)

[DPS Ammonite]

40 minutes ago, kgbudge said:

Geologists sometimes joke about "boundary faults" where formation names abruptly change across a state boundary due to different state geological surveys sticking with different names. This sometimes leads to some pretty heated arguments (see page 37 here.)

 

Oh the humanity! Now all the Chinle in Arizona will have to be renamed the Dockum? How could Texas do that to Arizona. The Painted Desert or Petrified Forest without the Chinle, never! Just think about the expense of changing all the brochures.

[RuMert]

This is interesting as different naming effectively nullifies the importance of formations as IMHO the meaning of the latter was to unite under one name the same fossils in different locations. Our scientists use formations much less, mostly citing ammonite zones and such, so that sometimes even finding a formation's name is complicated

Edited January 5, 2022 by RuMert

[FranzBernhard]

3 hours ago, kgbudge said:

"boundary faults"

Worse here, called "Blattrandstörungen", considered to be faults along boundaries of map sheets, bringing really different formations into contact with each other .

Franz Bernhard

[Troodon]

17 hours ago, jpc said:

Indeed, as Troodon mentioned, they are basically the same.  And when you get to Colorado it is called the Laramie Fm.  The Lance tends to have more big sandstone bodies than the Hell Creek.  The Lance also tends to have better skin preservation than the Hell Creek and therefore more 'mummies' come from the Lance... almost always associated with these sandstones.  Additionally (although this is geographic, not geologic) there is a ton more Hell Creek outcrops than Lance.  I have also found that preservation tends to be better on the Montana side of the border, which makes me sad.   

Hey don't forgot those Sauropods in the Lance 

[Troodon]

On 1/3/2022 at 1:53 PM, Nanotyrannus35 said:

So what is the difference between the lance fm and the hell creek fm? They both have the same dinosaur species and from what I can tell, other vertebrate species. The only difference that I can think of is that the lance fm is in Wyoming while the hell creek fm is in South Dakota, Montana, and North Dakota.

 

I know you are relatively new to this forum but its common courtesy to typically recognize the members that have taken the time to answer your questions you've posted here and in your other posts, whether you agree with them or not.   Just a thank you would be fine or click on one of the reaction emogies at the bottom of each post.    

 

[Nanotyrannus35]

On 1/9/2022 at 5:54 AM, Troodon said:

 

I know you are relatively new to this forum but its common courtesy to typically recognize the members that have taken the time to answer your questions you've posted here and in your other posts, whether you agree with them or not.   Just a thank you would be fine or click on one of the reaction emogies at the bottom of each post.    

 

Okay, sorry about that. Will do.