Groundwater

Groundwater is rain and snow melt that percolates into the ground and accumulates to a depth that depends on the amount of rainfall and/or snowmelt. This depth is known as the water table, which can rise and fall with the changing of the seasons.

Groundwater moves downhill, and where erosion cuts below the water-table level, there will be leakage of groundwater into a stream area (or, if the flow is low, there will be springs and seeps).

Groundwater moves very slowly; if pollutants are poured into the ground and reach the water table, it might take centuries for the pollutants to be flushed from the local area.

As depicted in the diagram above, each water well that takes out groundwater lowers the water table in the immediate vicinity of the well; if too many water wells are pumping out groundwater, then the water table will drop an the wells will have to be deepened = an expensive undertaking.

The topic of my next post concerns what happens to groundwater in limestone terrains. 

Hippochrenes amplus: an elegant gastropod

One of the more unusual looking but memorable middle Eocene gastropods (snails) is Hippochrenes amplus (Solander, in Brander, 1776). It is unusual because of its large and very wide “wing.” This genus belongs to superfamily Stromboidea and, depending on which researcher's classification system you choose to use, the genus belongs to either family Rostellariidae, the latter of which includes also the genus Tibia (see previous post), or belongs to family Hippochrenidae. 

The first picture shown here is a published sketch, made by Solander (in Brander, 1766), of a complete specimen of Hippochrenes amplus from England. 

The original name of this gastropod was Strombus amplus Solander. Solander (1733–1782) was a pupil of C. Linnaeus, the Swedish naturalist and originator of the Linnaean (1758) system of nomenclature of lifeforms. Solander's paper describing Strombus amplus might be the first time Linnaean nomenclature (i.e., a binomial name) was used to name a fossil. 

Solander's species was was later transferred to the genus Hippochrenes Montfort, 1810 (v. 2). This genus name is derived from the early 17th century, via Latin and from Greek, and refers to "hippocrene," literally "a fountain of the horse" (from hippos [horse] + krene [fountain]). The latter refers to a "fountain' on Mount Helicon,  sacred to the Muses. According to legend, the fountain was produced by a stroke of Pegasus' hoof (www.lexico.com). 

This next picture is of a specimen of H. amplus that I collected from an upper middle Eocene bed in southeastern England. It is 152 mm in height, but its fragile "wing" (along the right side of the shell) is mostly missing.

The next two pictures are also of an actual specimen (height 125 mm, incomplete) of Hippochrenes amplus collected by my colleagues from the same, above-mentioned fossil bed containing shallow-marine gastropods and bivalves in southeastern England, but, unfortunately, the specimen is not complete. Nevertheless, you can see at least half of its "wing," as well as  the whorls (revolutions) of the shell, except the anterior end of the shell.

Hippochrenes amplus is best known from upper middle Eocene (Bartonian Stage) strata in southeastern England. Specimens are known also from Eocene strata elsewhere in Western Europe. 

Tibia fusus: an elegant seashell

Tibia fusus (Linnaeus, 1758) is large seashell with an extremely long and narrow siphonal canal. Its shell has been called the "spindle tibia shell" or the “shinbone tibia shell.” This latter name is because of the resemblance of the long siphonal canal of the shell to the shinbone of a human leg. The tibia is the anterior (frontal) leg bone of the two bones in the leg below the knee.

The specimen illustrated here is 220 mm long (8 ¾ in.) and 34 mm wide (1 ¼ in.). Its precise locality is not known.

The largest reported specimen of T. fusus is 310 cm long (12.2 inches), including the long siphonal canal.

This first image is the front side (aperture) view.  The long siphonal canal is an open slit for the first 3/4 of its length; the rest of it is sealed on the outside.

Why the siphonal canal is so long is not known, but perhaps it allows the snail (gastropod) to be more stealthy when it is hunting prey. The siphonal canal is a sensory organ, and because its end is far away from the bulk of its animal/shell, then the prey might not be aware of the presence of the gastropod.

Notice the six "finger-like" projections on the outer lip of the aperture.

Tibia fusus is the type species ("the definer") of the genus Tibia. 

This second image is the back side (abapertural or dorsal) view.

Although most the shell of this species is smooth, its first 10 or so whorls are reticulated (cross-hatched by spiral and longitudinal ribs). This reticulation is a main characteristic of this species.



















This third image is a side view of the shell showing the outer lip.


Tibia fusus lives in offshore, tropical marine waters where there is an abundance of sand, at depths of 5 to 50 m. The species is known from the Eastern Indian Ocean and Western Pacific, especially from Indochina, China Sea, Taiwan, southern Japan, the Philippines to Indonesia, Australia, and Oceania. It is widespread because its embryos develop into free-floating planktonic larvae, which eventually develop into free-swimming juvenile veligers.

The image on the left is an enlargement of the aperture, showing the six "fingers" on the outer lip.
These fingers give the shell stability when the snail
is crawling around.

The image on the right is an enlargement of the outer lip of the aperture. Note how curved the "top" finger is. Its central part is grooved, so as to create a furrow.










The fossil record of T. fusus is Miocene (in France, Japan and Taiwan) to Recent. Most malacologists (scientists who study modern mollusks) assign genus Tibia to family Strombidae, wherea many molluscan paleontologists (scientists who study fossil mollusks) assign Tibia to family Rostellariiidae.

Two spiny seashells

I have always been impressed with the elegant beauty of very spiny seashells, and this post focuses on two of them. Both are trochid gastropods (snails) with a turban-shaped shell having a nacreous or mother-of-pearl interior. Trochids, which are herbivores [algae eaters], are now classified as vetigastropods, whereas in earlier (outdated) literature, they were classified as archaeogastropods. 

Angaria sphaerula (L. C. Kiener, 1839) is from coral-reef environments in the Philippine Islands area. Angaria belongs to family Angariidae, the so-called "Dolphin shells," and Angaria is the sole genus of this family. Angaria is characterized by having a reddish turbinate shell, with a depressed spire, and spiral ornamentation consisting of tubercles or nodules, which can be spiny. The stout and flattened spines along the top of the shell are used probably for mimicry to resemble coral growth, as opposed to the much smaller and sharper spines (most likely used for protection from predatory animals) found elsewhere on the shell. There is also a stout operculum inside the aperture (if you look closely in the first image below, you can see the dark-brown operculum. Other species of Angaria are known also from Indo-Pacific tropical waters.

Two views of Angaria sphaerula. The shell is 42 mm diameter and 31 mm high (including the spines) from the Philippines.


Guildfordia triumphans (Philippi, 1841), the so-called "triumphant star shell," is from relatively deep-waters (about 300 m depth) tropical waters off the coast of Japan. This torched gastropod has approximately 10 long and narrow spines radiating from the outside edge of its shell. These spines most likely provide support to keep the shell from sinking into the muddy substrate on which the shell lives.

Two views of Guildfordia triumphans, 65 mm diameter, from Japan.

For taxonomic details about the modern classification of these two vetigastropods, see WoRMS, World Register of Marine Species
<www.marinespecies.org>

Kuphus giant bivalve tube

Many years ago, while in a shell shop, I came across a large calcareous (calcium-carbonate) tube, about the size of a baseball bat. Although this tube resembled a giant "worm" tube, it is a tube made by an extant giant teredinid ("shipworm") bivalve that once lived in on the bottom of a muddy mangrove in tropical waters, most likely in the vicinity of the Philippine Islands.

The scientific name of this giant bivalve is Kuphus polythalamus (Linnaeus, 1767). It was originally by Linnaeus as Serpula polythalamia, but this name was later updated to Kuphus polythalmus. Yet, the incorrect spelling of the species name of Kuphus polythalamia is still used currently by many workers.



This first image shows the tube in question. This tube is 33 1/4 in. in length (the yardstick shown here is in inches).  The largest reported tube of K. polythalamus is 61 inches (155 cm) in length and 2.4 inches (6 cm) in diameter.

This image shows a closeup of the exterior of the tube near one of its ends, which is 2 in. in diameter.  


The life position of K. polythalamus is vertical  and with a tiny "Y" at its posterior end. Most of the calcareous tube is encased by the mud. At the anterior end of the tube (i.e., the widest part of the tube), there is a thin calcareous cap that covers the mouth of the bivalve. This cap must be resorbed periodically to allow the animal to grow. The cap had been removed by the time I got the specimen shown above. 

The maximum known size of Kuphus polythalamus is 155 cm (61 in. = about 5 feet) in length and 6 cm (2.4 in.)  in diameter. Thus, this bivalve is the largest known bivalve in the world. It lives in black, organic-rich muds (i.e., stinky) in mangroves/shallow bays in tropical and subtropical oceans in the Philippines, Indonesia, and Mozambique. This bivalve uses bacteria in its gills to convert hydrogen sulfide in the muds/water into nutrients. 

The top image above is a view somewhat downward into the tube and showing the incomplete posterior end of the shell I have. You can see the two holes for the siphons, side by side; one for intake of water, and the other for expelling water. Their fleshy ends would have extended into the water column above the calcareous tube. The branching part of the "Y" is at the narrowest part of the tube, where the two fleshy siphons stick out a short distance from the two holes, which as shown in the top image, are situated near the end of the tube, but within it. These siphons bring in water into the gills of the bivalve, and they can also expel water. 

The bottom image above is a view into down the anterior end of the tube, next to the mouth. A temporary cap at this wider end is missing. This end of the bivalve is stuck down into the mud during life. 

This giant bivalve is a member of the common wood-boring and wood-feeding bivalve family Teredinidae, which are among the least studied extant bivalves. Until recently, the biology of Kuphus polythalamus was very poorly known. You can now go online and watch a video all about this animal. Just type in the incorrect scientific name.

Kuphus has a fossil record of a few species, some of which are known from Oligocene/Miocene beds.

If you go online, you can watch a dissection of a K. polythalamus. It is taken from research by Distel et al. (2017). There is also a free pdf available for downloading.  

Diamonds

This post is the second part of a "two-parter." See my previous post on graphite, which is an allotrope of diamond. An allotrope is each of two or more different physical forms in which an element can exist. Graphite, diamond, and charcoal are all allotropes of carbon. 

Like graphite, diamond is a native mineral. That means it consists of one element, which is carbon, with a chemical formula of C. Diamonds are measured in terms of carats, which refers to a diamond's weight, not its size. One carat = 200 milligrams = 0.200 grams = 1/5 of a gram. The "largest" diamond known is the "Golden Jubilee" (5,000 grams).

Most  diamonds are Precambrian in age (between 3.5 to 1 billion years old). They are formed at high temperature and pressure deep in the Earth's mantle, mostly between 150 to 250 km (93 to 155 miles) depth. Some however come from as deep as 500 miles. They can be carried to the Earth's surface by volcanic eruptions and occur mostly in the plugged-up necks of ancient volcanoes, in rocks known as kimberlites. If the kimberlites become exposed at the surface of the Earth, they become eroded and the diamonds can be concentrated in stream or beach deposits. One of most famous diamond localities is from South Africa, where diamonds have been weathered out from kimberlites and concentrated as placer or "lag material" in beaches.

Diamonds (very small size) have also been found in some meteorites. 

Diamond is the hardest naturally occurring substance, having a rating of 10 on the Mohs Hardness Scale (0 to 10). The arrangement of  the atoms in diamonds is classified under the isometric crystal system, and the resulting structure is extremely rigid. Many diamonds are pure, and as a result they are transparent and colorless. Others can have color, caused usually by the presence of minute impurities. The range of colors (with increasing rarity), along with the known impurity or other factors causing the color, are as follows: yellow (nitrogen), brown (defects), blue (boron), green (radiation exposure), black (referred to as "Carbonado"), gray, pink, orange, purple, and red (most rare of all diamonds).

A diamond, or a simulant? It is 3.5 mm in diameter.

The image above shows a round, "brilliant cut" of what is probably a simulant (synthetic) and not diamond. I found it in a parking lot, and I spotted it about 20 feet away from me, because of its extremely bright and very eye-catching display of reflected light. Part of its mounting was still attached and consisted of hardened copper.

I spent considerable time and effort in trying to determine if what I found is truly a diamond, or if it is a simulant (synthetic or "fake"). 
I tried all the "easy" tests [e.g., water, fog, scratch, newsprint], all of which have been shown as videos on the internet, to determine what I found, but the tests were not conclusive for my mystery "stone." 

There are several types of simulants (note: they are much less expensive that diamonds). Two of the most common ones are moissanite (silicon carbide) and cubic zirconia (zirconium dioxide). 

Moissanite is a very rare naturally occurring mineral, but most of it that is used to make jewelry is created synthetically in a lab. It has a hardness of 9.5, colorless and has more brilliance (flash-of-light, or "fire") than diamond. It is one of the best substitutes for diamond.

Cubic zirconia is an entirely lab-created substance. It has a hardness of 8 to 8.5, and it can scratch easily.  

Based on the fantastic brilliance in natural light of my mystery stone, as well as on the copper mount, I believed that it is probably moissanite and not a diamond. As I viewed numerous websites about diamonds and simulants, I discovered that some simulants can look really good. I discovered eventually that the best and most definitive way to distinguish between a cut diamond and the various simulants is to consult a gemologist or a reputable jeweler. Using a very precise machine, they will weight the material in question and compare it with a comparable-sized diamond. This kind determination will be reliable.

Graphite

This post consists of two parts. The first part is about graphite and the second part is about diamonds.

Graphite and diamond are native element (ones that consists of a single element). Like graphite, diamonds consist of pure carbon. These two natural forms of the element carbon (C) have the greatest contrast in structure and properties to be found in any pair of polymorphous substances.

Graphite has its atoms arranged in a hexagonal structure, which forms sheets that are poorly connected, thereby allowing the sheets to easily slide over one another if subjected to a small amount of force. Thus, graphite is slippery and greasy. That is why it is used in pencils (as in "lead" pencils) and also is used as a lubricant. Graphite is, furthermore, light, extremely soft, inert, and highly resistant to chemical changes. Graphite is a good conductor or heat and electricity and is used for making solar panels, batteries, and electrodes.

                       Specimen of graphite (3.2 cm from bottom to top of image).

Graphite forms predominantly in rocks affected by regional or contact metamorphism, and it is found in crystalline limestone, metamorphosed coal beds, schist, gneiss, quartzite. Locally, it can form in veins (pegmatites). Under high pressure and temperature, graphite converts to diamond. Graphite has been found also as minute crystals in some meteorites.