Amber and entombed insects

Amber is fossilized resin that blocks gaps in tree bark, especially conifers. It is not the same as sap, which transports nutrients through the heartwood of trees. Amber is very sticky and insects can be trapped in it when they try to burrow or eat the bark. When a tree limb is injured, amber can exude as blobs or drippings and flow down the side of the trunk. Insects can easily be engulfed or trapped in the resin, which commonly falls onto the ground and becomes incorporated into the soil. Other small animals, like lizards, frogs, birds, and even bats have been found in amber. Only a few tree resins (e.g., Kauri pine in New Zealand) can form fossilizable amber. Hardened resin is called copal, and it is easily transportable in streams and rivers, where is becomes part of the non-marine sedimentary record. In some cases, it can be transported into the nearshore-marine environment.

A polished specimen of copal (6 cm width);
 where collected unknown.

The transparency and color of the specimen shown above are typical for most amber. Bubbles, which are also commonly present, make amber lightweight and, in some cases, even floatable in water.

 

Left image: leaf (1 cm long) in specimen of copal shown above.

Right image: bug (7 mm, maximum length) in specimen of copal shown above; with wings and legs intact. 

Left image: Another polished chunk of copal (8 cm length, notice thumbnail--for scale--on left side of image); where collected unknown. Enlarged image shows a termite? (4 mm length) and below that, another insect, both found in the chunk.

These two pebbles, both polished, shown the typical range of color (hue) of most copal. The smallest piece is 1.5 cm in height. Both are from the Baltic Sea area, Denmark. No insects are present in these two specimens, which shows that not all copal has to have insects.

Copal is used in making jewelry and also in rosary beads. Copal is relatively soft, however, and can be scratched by a hard surface. When buying copal, the more insects (inclusions) present means that the price goes up. A word of caution: so-called "copal" can be made out of look-alike plastic.

The oldest known copal  is Late Paleozoic (Late Carboniferous, Pennsylvanian-age coal beds). The oldest copal with insects is Early Cretaceous (when the first flowering plants appeared).

Hyolithus: a Cambrian mystery solved

Preliminary comments: The fossil Hyolithus has long been an enigma. Is it a mollusk, a worm, or what? When I first started teaching, it was strongly favored to be an early mollusk. It remained in that uncertain mode until recently when a team of paleontologists (Moysiuk et al., 2017) collected over 1,500 specimens from British Columbia. Remarkable specimens were found that show, for the first time, soft-part anatomy impression. Now the mystery is solved. Read on to found out what the answer is.

Impression of a fossil specimen of the hyolithid Hyolithus cecrops Walcott, 1917 (19 mm height, early middle Cambrian, northwestern Montana). Found with specimens of trilobites [Albertella helena], brachiopods, and trace fossils.

Hyolithids are a group of small, somewhat flat-shaped, shells whose biologic affinities have long been uncertain. The most common assumption was that they were gastropods, which had a planktonic (floating) existence, like the pteropod gastropods (so-called "sea butterflies") found in modern seas. Their most perplexing morphologic feature were the two "oars," which are now named "helens." In the image shown above, only the left helen is preserved.

Most of the several hundred species belong to genus Hyolithus, which had a worldwide distribution, starting in Early Cambrian time. They became diminished during Ordovician and lingered thereafter until the Middle Permian.

Dorsal view of exterior of H. cecrops showing the major morphologic characters.  

Side view of exterior of H. cecrops. The operculum (lid) could open slightly, and the feeding apparatus (probably similar to the lophophore of some modern animals), could then be extended into the water column. The helens were used as stilts/props for holding the animal above the muddy bottom substrate. 

Dorsal view of interior of H. cecrops, showing critically important soft-tissue impressions: the presumed lophophore, the location of the mouth, and the U-shaped gut. These impression are indicative that hyolithids were not planktonic mollusks. Instead, they were benthonic (bottom dwellers) animals that had their closest relatives being the lophophore-bearing brachiopods and bryozoans. 

For more information see:
Moysiuk, J. et al. 2017. Nature v. 54:394–397 (like other pay-for- subscription journals, the abstract is free, but it costs to read or download the actual paper).

Tektite, an interesting rock

Tektites (pronounced tek-tites) are the by-products of meteorite impacts on Earth.  Composed of gravel-sized, natural glass particles, which are predominantly black, they can also be brown, gray, or green. They made up of natural glass formed from molten terrestrial debris thrown into the air after a meteor strikes the ground. Tektites have no crystalline structure because they cool so rapidly, thus crystals cannot grow. In that sense, they are similar to obsidian (volcanic glass), but tektites have lower water content than obsidian glass.

A tektite (4 cm length) from Guang Dong, Kwangtung Province, China.

Tektites occur within “strewn-fields” associated with meterorite impact craters. Some of the more famous “strewn-fields” are in southern China, the Czech Republic, and the Ivory Coast of Africa (Ghana).

If you check online, you can find tektites for sale, at a modest price in most cases. For more information about tektites, see <www.britannica.com>

Salton Sea concretions

Along the southwest side of Salton Sea, northeast of San Diego, in Imperial County, southern California, sandstone concretions weather out in abundance from outcrops of the non-marine Borrego Formation of Pliocene age (about 2 million years old). These concretions have a variety of shapes, and some are very unusual. A selection of the shapes is shown here.

The largest concretion (the one that looks like a rabbit's head) is about 18 cm long (about 7 inches).

Concretions like these form by waters percolating through sediment. Over time, dissolved minerals in these waters cement
the sediment together and create these bizarre shapes. Some of the concretions found in this formation can several feet in size.

A Titaniferous Magnetite Boulder from Southern California

A few days ago, a 1-foot-long blackish boulder weighing about 40 or 50 pounds was shown to me in order to get my opinion as to its origin.

The definitive answer about this boulder came from fellow geologist Dave Liggett, whose was kind enough to help me and whose knowledge of igneous petrology (especially of the southern California area) is phenomenal. The rock you see below is actually a "meteor-wrong" instead of a meteorite.

A close-up of the rock specimen shown above.

Here are the particulars. It is a worn boulder of titaniferous magnetite (iron + titanium + oxygen), probably with intergrown crystals of the mineral ilmenite. The boulder is most likely from the western San Gabriel Mountains, in the Los Angeles National Forest, north of Pasadena, southern California. The geologic age of this rock is Precambrian (several billion of years old). Mineralization in this area is hosted by the rock anorthosite, which will be the subject of one of my future posts. This anorthosite body comprises a 82-square mile area, in which there are many old mines, including some abandoned gold mines (now on private property). The magnetite in this host rock occurs mostly as irregular or dike-like bodies with either sharp or gradual contacts with the anorthosite.

F.Y.I., it seemed to me at first glance that it could be a meteorite. It is very heavy, hard, and magnetic. Those features by themselves, however, do not prove that it is a meteorite. To see a very useful and educational "yes/no" flow chart for trying to decipher whether a rock is a meteorite, I highly recommend a website maintained by Randy Korotev, who used as a basis for comparison, images of meteorites housed in the Department of Earth and Planetary Sciences at the Washington University in St. Louis.

Black Onyx

Black onyx is variety of chalcedony = cryptocrystalline quartz. In a previous post on September 14, 2018, I focused on the subject of cryptocrystalline quartz, so please look at this post for background information. Just use the Search box in my blog and type in the word chalcedony.

Black onyx starts out as multi-colored, banded chalcedony, which would normally be called agate, a silica-rich material. By means of a human-induced chemical process, the bands are eliminated, and the “stone” becomes solid black. It is not a dyeing process. Instead, the blackening process takes places when carbon is introduced into the “stone” via a sugar-acid reaction.

As a result, beautifully looking, pure-black “stones” are created. They are used for making jewelry, which can be expensive.

Black onyx cuff link (15 mm diameter)

Black onyx should not be confused with similar terms which involve calcium-carbonate minerals and have entirely different (natural) origins. Examples are Mexican onyx (see image below), limestone onyx, travertine, and onyx marble. These are much softer than black onyx (silica) and also fizz when drops of 10% hydrochloric acid are applied to them.

Mexican onyx (white and black layers) from central Arizona
 (USA penny 18 mm diameter)

Also, although the extrusive volcanic rock obsidian is black (see my previous post on volcanic igneous rocks), and the variety of quartz known as “smoky quartz” is cloudy-black (see another one of my previous posts on macro-crystalline quartz), they are not the same as Black onyx.

Biologic and Paleontologic Online Videos

In the past week or so, I have been fortunate enough to learn about some very useful and informative biologic/paleontologic online videos, which I wanted to let you know about. In my opinion as a former teacher for many decades, both series of videos are worthy of your interest and attention if you are a teacher or a student.

I cannot link them directly because Google no longer supports that option on their format for blogs. But, they can be easily accessed by typing in a few words on your search-engine browser.

The FIRST SOURCE has 30+ teaching/learning videos about topics dealing with Biodiversity (e.g., An explanation of what DNA is all about; How climate change affects biodiversity; etc). The videos are informative and easy to follow.

Google: California Academy biodiversity course

This course is available through the Academy’s YouTube channel.

The SECOND SOURCE has colorful, high-tech videos depicting the evolution of the animal kingdom on earth (e.g., The 3-D anatomy of the chambered pearly Nautilus; etc.).

Google: https://www.shapeof life.org

If that does not work, the full URL for the Nautilus animation is:

http://www.shapeof life.org/video/mollusc-animation-nautilus-body-plan