NH Notes: A Fossil Scallop from Calvert Cliffs, MD

A colleague has a fossil scallop in his office that he collected while teaching a field course on Chesapeake Bay biology.  He pulled this scallop from the cliff wall at Calvert Cliffs near Calvert, Maryland. It is particularly impressive not only for its size (more than 5 inches in diameter) but also for its condition.  But what caught my eye was what was attached to it (see below).   This fossil scallop is thought to be not much more than 10 million years old, so is a youngster in geological terms.  As such it demonstrates some features of “younger” fossils that are typically not appreciated.   Let me share some pictures I took of this fossil and then provide the geological context for where it was found.

Large scallop collected by a friend from Calvert Cliffs in Maryland.  Image: Joel Duff

Large scallop collected by a friend from Calvert Cliffs in Maryland. Image: Joel Duff

This was the side facing down.  The top side is more interesting as shown in the images below.

Top side of the same scallop as above showing several large barnacles attached.

Top side of the same scallop as above showing several large barnacles attached.

Here is a picture of the topside of the scallop.  Two things to notice here: First, there are several large barnacles that are attached to the top of the shell.  Several of them were damaged during the extraction of the shell from the cliff wall.  The second is an orange discoloration on the top part of the shell and one of the barnacles.  This represents the portion of the shell that was exposed on the cliff face for some time and became stained from chemicals that leached out from the rocks and soil in the layers above and ran down over the face of the cliff.

Calvert Cliffs along the Chesapeake Bay in Maryland. http://camano130.blogspot.com/2010/05/family-and-friends-through-maryland.html

Calvert Cliffs along the Chesapeake Bay in Maryland. http://camano130.blogspot.com/2010/05/family-and-friends-through-maryland.html

Just what are the Calvert Cliffs?  They are a long set of cliffs along the western shores of Chesapeake Bay in Maryland south of Washington D.C..   As the bay erodes the cliff wall new fossils are continually revealed and collectors come to find shells, sharks teeth, corals and even the occasional whale bone.   Fossils densities can be very high with many billions of shells certainly preserved here.

Are these really fossils?

Looking at these pictures you may wonder if this is really a fossil or just a shell buried in some sand hundreds or thousands of years ago.   The term “fossil” is not easy to define as the process of becoming a fossil is not made of discrete steps but rather is a gradual process.  The shells here retain much of their original molecules rather than having been replaced by minerals.  So they are not “rock” in the sense of many older fossils.  Nevertheless they are best thought of as fossils because they are imbedded in rock and their chemistry is altered. These are not like shells that you would find on the beach or even shells that are thousands of years old that you could dig out of an old beach in Florida for example.  This fossil scallop is very heavy as it has been at least partly mineralized.

barnacle-scallop-side1000pxA shot of the base of the scallop showing just how well preserved this scallop is and how the barnacles are attached to it.

scallop-closeup-ridges-2000pxThe detail in preservation is really amazing

scallop-calvert-cliffs-closeup-ridgesThis is a close-up of the ridges of the scallop showing the mineralized surface.

Close-up of the ridges of the fossil scallop

Close-up of the ridges of the fossil scallop

Shells in the cliff wall at Calvert Cliffs along the western shore in Maryland. This and many other images of shells from this location can be found here: http://home.comcast.net/~rdchdwck/fossils/cenozoic/calvert_cliffs.htm

Shells in the cliff wall at Calvert Cliffs along the western shore in Maryland. This and many other images of shells from this location can be found HERE

Where did all these shells come from?

Why are there many meters thick layers of rock embedded with billions of shells and sharks teeth found at this location and how old are there?  Look at the picture to the right.  Shells are stacked on top of each other many meters high.  In many locations the shells are mostly broken, show signs of predation like bore holes and are covered with barnacles.  Geologists who have studied this region believe that this entire area was covered by a shallow sea when the Earth was warmer and the ice caps were melted.  At that time shells would have accumulated on the sea floor and especially near shorelines.  Erosion of the Appalachian mountains would have continued to introduce new sediments into the sea covering the shells and allowing for their preservation.  Shells are thought to have accumulated at this location for hundreds of thousands of years.  Eventually the Earth cooled and the ice caps reformed lowering the ocean surface by hundreds of feet.  Erosion via rivers then cut through what was once the ocean bottom.  Today the Calvert Cliffs are one place we are able to see the remains of these layers of sediments now turned to a soft form of sandstone rock  (sandstone is like a fossil, it forms through a gradual process of cementation and this sandstone isn’t well cemented so easily broken and worn).

Aproximate area covered by shallow ocean in the past.  This embayment would have been very shallow.  Redrawn by Sandy Rodgers from figures in Clark et al. 2004

Approximate area covered by shallow ocean in the past. This embayment would have been very shallow. Redrawn by Sandy Rodgers from figures in Clark et al. 2004

Creationist’s Geology Challenged Again

I’ve said that geologist believe that the rock layers of the Calvert Cliffs are 8 to 20 million years. Obviously young earth creationists (YECs) can’t accept those dates.  Georgia Purdom, staff scientist for Answers in Genesis, has questioned the age of this formation by questioning the validity of radiometric dating. But she and others YECs completely miss the forest for the trees.  Radiometric dating is just a red herring here.   They need to deal with the actual fossils and what those fossils are telling us about their past.

To compress all the geological formations of the Earth into a few thousand years requires some extraordinary events.  YECs think they have that extraordinary event in Noah’s Flood but does that really explain a formation like the Calvert Cliffs?  Not really.   There are 20,000 feet of fossil-bearing sediments below these cliffs.  Are we to believe that this large scallop with its barnacles survived the turbulence of a global flood only to be deposited at the very top of the geological column without so much as a scratch?  This is not reasonable. In fact, even YECs  who look at the geological context and the condition and types of fossils here would likely conclude they are not the result of a global flood.   Rather would likely appeal to some sort of post-flood events but that would put their origins sometime less than 4500 years ago!  Even so these shells do not appear to be laid down by any large event but by natural everyday processes of a shallow seabed.

Clearly this area of Maryland was covered by a sea and YECs might be tempted to accept this as well but this causes a problem. They have been promoting the theory that there was a global ice age right after the global flood. If this was the case then the ocean levels would have been hundreds of feet lower rather than higher.  There is no place in their theories for the creation of this particular layer of fossils.  These fossils form the remains of organisms that are clearly all from a particular ecological setting. That setting is one of a shallow and very warm ocean that suggests a time when the Earth was much warmer. A warm Earth is completely consistent with the ocean being hundreds of feet higher at this location at the time.   The fossils are all of organisms that are considered modern rather than long extinct things. All of these observations about the Calvert Cliffs fossils are completely consistent with the millions of years old estimated dates of the rock.

So where does this scallop fit into the YEC view? I have no idea and I don’t think they do either.  They will simply avoid the specifics and point to possible issues with radiometric dating as if casting doubt on a date will prevent all other questions.


  1. Virginia Peterson says:

    Another historic factor you didn’t mention was the crater in the area, which I presume underlies all this sediment? Does the black line in the map drawing above roughly correspond to its location?


    • I was thinking of that when I included that figure but decided that it would take too much explaining. The crater is actually a bit south of this point but the whole area was definitely effected by it. Snelling at AIG acknowledges that this crater is definitely caused by a meteorite and thinks it happened in the last days of Noah’s flood or even later. This would then place the origin of these layers that make up these cliffs as being later (eg. less than 4500 years). So when was this area covered by a sea after Noah’s flood, I have no idea. Makes no sense but that is what happens when they make up theories to fit one piece of data without considering other data.


  2. Ray Zink says:

    If Jesus could turn new wine “un-aged wine” into good wine… “Aged Wine” then why could God not have created an new universe as if it was aged? Darwin’s theory has been debunked as current magnification of Cells show they were constructed of “Parts” and as we all know parts can not assemble themselves… Just pointing out that no one really knows all the answers. Science and Faith do have a common thread as they both seek the truth and both can be blinded by not remaining open to new science and new Revelations… after all no Science is 100% or it is not truce Science that seeks the truth.


    • Hi, thanks for the comments. If He did then his “aged” universe has no sign of global flood and was made to appear as if there weren’t one. This won’t help solve any problems but may create a lot of new ones. I suppose no one really knows the answers but God didn’t create a nonsensical world in which nothing could be known but he created things with structure and order. I can’t prove you exist. This message I am responding to might have been random electrical signal that happened for form words. But that wouldn’t be a reasonable thing to believe but I certainly can be 100% sure that it isn’t. However, I won’t lose too much sleep worrying if the comment is from a real person or not.Its late and time for bed:-)


  3. Audrey Nielsen says:

    What was the method of dating used?



  1. […] And finally, here’s Joel Duff discussing a cool fossil found in the Calvert Cliffs of the Chesapeake. As always, Duff provides an interesting discussion of the fossil itself and then segues into why […]


  2. […] Here’s more detail about the rich fossil world of the Chesapeake. […]


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