THE BOTTOM OF A JURASSIC SEA: PHOENIX

At times I have a little trouble with the correct (so they say) pronunciation of certain similar sounding words.  I blame this fault on growing up in a small Kansas town where all the kids had a twang.  For example, creek (a small stream) was pronounced “crick” that was also a noun referring to a stiff neck—"I left the window open and woke up with a crick in my neck.”  One of my bad problems was wonder and wander--there is only one letter difference so perhaps I could be forgiven?  

Wander is a verb meaning “to move about without a fixed course, aim, or goal” (Merriam Webster Dictionary).  Wonder can also be a verb “to feel curiosity.”  For much of my life I have been wandering while wondering! 

This verb duo hit me one day while visiting the Superstition Springs Mall in Mesa, Arizona.  Now, I am not a “mall person” but did mosey in to purchase a cup of coffee and check out the “good German fossils” that a unknown rockhound in Germany had suggested as a little field trip!  He had emailed me since after reading my Blog and knew I was in Tucson and might enjoy some nice rocks and fossils!

At first, I just sort of blanked out as is my custom upon entering one of these shopping behemoths.  Straight to the coffee shop and then find a bench, and so I did without any thought in my brain.  But then my mind began to wander and also wonder---where were the German fossils?  So, I raised off my fanny and my legs began to wander while my brain kept wondering---perhaps there was some sort of a display of vertebrates in the courtyard?  But wait, what was right in front of me? Could it really be?  Yep, I was looking at the bottom of a shallow Jurassic sea with all sorts of wonderful marine creatures looking back.  Well, they were not really moving around and looking but were encased in the beautiful polished limestone that was used as floor tile in this humongous building.  I immediately thought what a wonderful place it would be to bring a group of young children and let them look at, and hear about, the wonders of nature.

So, I began to wander around in my one little corner and hallway taking a great interest, and several phone photos, of these beautifully preserved fossils.  I was sort of wandering around in a typical rockhound style bent over and searching while perhaps 300 people ignored me, and many gave me a wide berth.  Now, I was dressed in decent clothes, and had shaved that morning so as not to embarrass my accompanying companion, but several persons actually seemed scared of my actions.  I was really hoping that at least one family with children would have asked, “hey Mister, what are you looking at?’  But, no such luck.  Think what would have happened if my knees were good and I had assumed the stance rockhounds use when hunting for tiny peridot crystals?  I would have been hauled off by Paul Blart, Mall Cop. 

It turns out that I had seen this limestone before—in a museum, and in Germany.  It is called the Jura Limestone or Jura Marble (from the Jurassic Period and Jura Mountains) and is quarried in great quantities from southern Bavaria in Germany.  It is also packed with spectacular fossils of ammonite cephalopods, corals, sponges, echinoderms, worm burrows, amazing belemnite cephalopods, and may other creatures I could not identify in a short time span.  It is my understanding that some vertebrates (fish and reptiles) have been found in the unit. The building stones/tiles also come in several different "color shades" but the most common are tans and grays (in the trade each color variety has a specific name).

Why was this limestone being walked on in southern Arizona? It seems as if the rock is quite hard, takes a nice polish and is shipped around the world for use in heavy traffic areas as floor tiles, counter coverings, entrance ways in hotels, etc.  Evidently my unknown friend in Germany had visited the Mall and wanted me to take a peek at good German Fossils. 

In reality the Jura Limestone is a trade name for this spectacular rock while the geologic moniker is the Treuchlinger Formation and is Late Jurassic in age (Kimmeridgian ~157 Ma--152 Ma).  The Jura Limestone is quarried in the same general area as the slightly younger, and more famous, Solenhoffen Limestone (Tithonian, ~ 152 Ma--145 Ma) with its famous fossils, including “Archaeopteryx”.  Both of these quarried building stones are products of the widespread Tethys Sea that covered Europe for much of the Mesozoic Era.

In looking at the accompanying photos note the wide variety of what appears to be remains of soft bodied animals.  But, perhaps some of the “things” I thought may be body fossils may simply be “worm” burrows.  The only two that are certain are the hard-bodied belemnites and the ammonites, both cephalopods.  I can offer speculations on a couple of others.  This limestone is so amazing with such a wide variety of fossils and other structures. 

Unfortunately, I cannot, at this time, locate a copy of Hans Bantz’s 1970 book describing the fossils of the Jura Limestone from the Franconian Alps (Der Fossilinhalt des Treuchtlinger Marmors (Mittleres Unter-Kimmeridge der Südlichen Frankenalb).  Fortunately, I am writing this offering while camped at one of the most beautiful place in the U.S., Monument Valley in Navajo Tribal Park (southeastern Utah).  Not only is Baltz’s book unavailable, so are newspapers, television stations, internet service, telephone service and noisy railroads.  What is available are fantastic sunsets and sunrises, amazing red rock scenery, crystal clear night skies with a full moon, and a real quietness.  Life is good.

The above two fossils are ammonoid cephalopods perhaps of the genus ?Progeronia.  Note penny for scale on top photo.

The above three specimens may be sponges.  I am fairly certain the lower photo is a sponge of some sort.  Note penny for scale.

A cartoon of belemnite anatomy courtesy of Phil Eyden at: www.tonmo.com/pages/belemnites/.

The most amazing specimens in the floor tile are the rostra of numerous belemnites (Cephalopoda) belonging to the genus Hibolithes.  Belemnites range from the early Jurassic until extinction at the end of the Cretaceous.

This specimen is interesting but what is it?  The upper part is "cut off" by the end of the tile.  Is that an attachment structure at the "bottom" of the animal?

The above three photos--burrows? "worms"?

You name it and it is all yours!

The above two specimens, above and below, seem related as it appears there are hard parts present.  But what is it?

And I leave you with a "normal" winter sunset as viewed from the campground.