“Marble Machine” and “Pipe Dreams”

I am currently taking a break from writing TumbleStone Blog posts while I am busy selling my home and buying a new place near Whanganui. A diversion for those wanting to look at something in the interim…

An amazing machine making music:

A digital animation along the same lines:


“Here Is Where The Heart Is… Sea Winds Out On The Wild”

Out on the beach, in the wild wind and salt spray, the waves roaring in, the wet stones glistening in the winter sun – my Scottish ancestors must have known something like this…

Photos from the last three days spent by me on Gemstone Beach, finding many fossil worm cast stones, a lot of them too big for tumble polishing…



Wolfstone’s song (below) expresses Scottish ties to land, coast and sea, as well as their disruption and loss through the Clearances and emigration. Runrig’s song (further below) speaks of the modern Scottish recovery of identity and the struggle for more control over national direction.

“Here Is Where The Heart Is” by Wolfstone

Here is where the heart is, beats out like a drum
Here is where the Mavis* flies, where she once came from
Here is where the mother tongue resides,
Far from the hands of hate and greed and lies.

This is where my home is, the shore, the sea, the sand
This is where my family were raised from working hands
This is where the toil and sweat and tears
Knew only hardship through those working years.

From farm and croft and residence, they cleared them from the land
Families of young and old with one wave of a hand
Were sent on board to sail the ocean wide
To a stranger’s land o’er wind and sea and tide.

Here is where the heart lies, like those who’ve been before
Here there are no broken ties with brothers on the shore
Here is where the spirit will return
No more to sigh, no more to weep and mourn.

Here is where the heart is, beats out like a drum
Here is where the Mavis flies, where she once came from
Here is where the mother tongue resides,
Far from the hands of hate and greed and lies.

*”Mavis” = Song thrush.

Recovery” by Runrig

Watching the morning come in on the land
See the moon roll over Skeabost
See the young men late in the glen
All with camans* in hand

Sea winds out on the wild
Sea waves crash onto Uig
See the black homes strung out in a line
Across the island of Skye

I can’t believe
That it’s taking all this time
I can’t believe
My life and my destiny
After the clans, after the clearings
Here I am

Should have been home before daylight
It’s not easy when you’re down and hungry
One from the late run rolled up in a coat
I make my way across the moor

For a late summer in ’84
But now there’s a new day dawning
I’ve heard the Braes men talk in Portree
The news from Glendale

And I can’t believe
That it’s taking all this time
I can’t believe
My life and my destiny
After the clans, after the clearings
Here I am

Still the morning comes in on the land
See the new sun red and rising
See the corn turn ripe in the fields
See the growth in the glen

And MacPherson’s in Kilmuir tonight
What a night for a people rising
And oh God, not before time
There’s justice in our lives.

*”Camans” = The sticks used in the game of hurling.

Visiting the South Coast

I am currently based in Riverton for a few days. The rough weather is restricting stone collecting. Had a brief visit to Gemstone Beach yesterday morning, where the waves were powerful and it was not possible to get past the Taunoa Stream. Made another quick trip to the Back Beach at Riverton late yesterday afternoon and found some nice fossil worm cast stones with the help of my sister Helen. Weather is windy and cold, and a storm this morning prevented a planned trip to the Orepuki area, but it will improve, hopefully…

The Fossilised Worm Cast Stones of Gemstone Beach and Riverton – Part Four: Ichnogenus Protovirgularia and the Permian Rocks of the Eglinton Valley

It can often be difficult for the non-expert like myself to identify a stone. Consulting books or the internet about different rock and mineral types can be frustrating because you can often find three or four possibilities that might match your stone. Moreover, your stone might have some characteristics that appear to be unique and not present in any of the “pure” types included in the books. There may be clues in how locals refer to a stone, though even they can be mistaken. You may be lucky enough to come across a reference to your stone by an expert somewhere, or you might even be fortunate enough to contact an expert who can help you.

This Post is part of a series on what are called “fossilised worm cast stones” found on Gemstone Beach and the beaches of Riverton in Southland. I have not come across any authoritative reference to them anywhere in the literature or online. Until now. Recently I received information on them from two different sources. This Post reports on the first source, and the next Post reports on the second. (The first Post in the Series can be found here.)


In early July I emailed the following seven photos to someone I know in a University Department of Geology.

“The stones contain what are probably fossilised traces of worms”, I wrote. “I would like to identify the kind of rocks the stones come from, what kind of worm is involved, and when they were active (in other words, when did they start becoming fossilised).” My inquiry was passed on to another geologist with expertise in ichnology (the study of trace fossils) who replied: “Yes, a trail, probably ichnogenus Protovirgularia, usually attributed to a small bivalve such as Nucula. I’ve seen it in float boulders in the Eglinton and very similar pebbles on the East shore of Te Anau, where it is likely from the Permian.”

It seems to me that five points follow from this information:

1) The traces on the stones are trails . If this term is taken strictly and narrowly, then a “trail” is left behind on the surface of sediment by the movement of an animal. A “trail” is not a “burrow” nor a “cast” (excretion). However, a looser definition of a “trail” could include “burrow” and “cast”, so it is important to keep an open mind on this.

2) The trace is called ichnogenus Protovirgularia. My initial research into this term reveals the following. “Ichnogenus” is a category of taxonomy (a way of grouping similar things) for trace fossils. A “genus” is an intermediate category between “species” and “family”. In relation to the term “Protovirgularia”, “Virgularia” is a genus of sea pen in the family Virgulariidae (sea pens were discussed in Part Two in this series of Posts), and “Proto” means original, primitive, first or earliest. For a number of weeks I was not able to find out why this group of trace fossils was given the term “Protovirgularia” – I thought that maybe it was initially thought to have been made by a sea pen. It is reasonably well-established now that in the vast majority of cases the pattern is made by bivalves, though it can be made by other invertebrates (this may be the subject of a later Post). I was eventually able to find a copy online of the original article that first identified protovirgularia. It was written by Frederick McCoy (Professor of Geology and Mineralogy, Queen’s College, Belfast) in 1850 in the “Annals and Magazine of Natural History“. On page 272, McCoy wrote: “…In the form of its axis and the structure of the transversely ridged celluliferous pinnae, both in the curved extended, and in the straight contracted states, it perfectly resembles the recent Virgularia mirabilis…” (my underlining).

McCoy 1850 ab
Source: https://www.biodiversitylibrary.org/item/102950#page/302/mode/1up

In his 1850 article, McCoy also referred to Protovirgularia dichotoma which varied a little from the basic Protovirgularia he first described.

Below are photos of Virgularia mirabilis, also known as the slender sea-pen. The photo of a dead one on the far right below shows the resemblance noted by McCoy to the fossil he had observed, and he believed it to be of a primitive ancestor of this animal. It was not until 1958 that the fossil was identified as a trace fossil made by a different animal.

One academic source defines ichnogenus Protovirgularia as a small keel-like trail which is composed of an elevated median line and lateral wedge-shaped appendages alternating on both sides (see also the entry in FossilID). The following description of Protovirgularia dichotoma is very interesting in relation to the trace fossils found at Riverton and Gemstone Beach because of reference to chevrons (v-shaped patterns). This source describes Protovirgularia dichotoma trace fossils as “horizontal or subhorizontal cylindrical burrows, trapezoidal, almond-shaped, or triangular in cross-section, distinctly or indistinctly bilobated [having two lobes]. Internal structure, if preserved, is formed by successive pads of sediment that may be expressed as ribs on the exterior. Ribs arranged in chevron-shaped, biserial pattern along external or internal dorsal part.” Below are examples.

pv dich slide
Examples of Protovirgularia dichotoma from Spain. Source: https://www.slideshare.net/JordiMaria/bivalvia-2006-tt-compr

The photo below contains four examples of protovirgularia trace fossil specimens from Japan, discussed in a 2011 article in the academic journal “Palaeogeography, Palaeoclimatology, Palaeoecology”. The variations within the protovirgularia grouping is shown. Note too that these are three-dimensional traces in contrast to the trace in the Gemstone Beach and Riverton stones that have been subject to “flattening” by the smoothing action of the river and ocean.

Protovirgularia trace fossils from Japan. Source: Page 3 of https://www.academia.edu/849702/_Deep-sea_bivalvian_highways_An_ethological_interpretation_of_branched_Protovirgularia_of_the_Palaeogene_Muroto-Hanto_Group_southwestern_Japan

The diagram below is from a 2010 article on protovirgularia found in Patagonia, Argentina, published in the “Journal of Paleontology”. Again, the significant variety in the forms of this trace shape is demonstrated. Forms #3, #4 and #5 on the diagram look at first sight to be closest to the well-defined chevron shaped traces often found in the Gemstone Beach and Riverton stones.

carmona et al fig 4
Morphologic variations of Protovirgularia. Source: https://www.researchgate.net/publication/240776411_Taphonomy_and_Paleoecology_of_the_Bivalve_Trace_Fossil_Protovirgularia_in_Deltaic_Heterolithic_Facies_of_the_Miocene_Chenque_Formation_Patagonia_Argentina

3) Despite its name linking it to sea pens, it seems that this type of fossil trail, “ichnogenus Protovirgularia”, is usually thought to be left behind by a small bivalve. A “bivalve” is an aquatic mollusc which has a compressed body enclosed within a hinged shell, such as a clam, oyster, mussel, or scallop. Bivalves have inhabited the Earth for over 500 million years. They especially flourished in the Mesozoic and Cenozoic eras (the last 250 million years). The excellent British Geological Survey entry on bivalves as fossils shows how they are able to burrow into sediment. One article in the journal “Ichnos” in 2010, again on protovirgularia from Argentina, gives the following account of the link between the trace and bivalves: it is a locomotion trace produced by bivalves, a burrow resulting from the rhythmic action of a muscular cleft-foot (page 42). Nucula is a genus of very small saltwater clams, according to Wikipedia (see photo, below left, of Nucula in Te Papa Museum and, below right, Auckland Museum).

These clams are very ancient, having been around for the last 450 million years or so, and have been very common around the world. They can reach a size of up to 30 millimetres and  live in the muddy sand close to the sediment surface at an oceanic depth of 20 to 200 metres. It is thought that the movement of Nucula leaves behind the “ichnogenus Protovirgularia” trace shape. However, I assume there is also the possibility that maybe something else could leave that trace shape.

4) The trace fossil shapes found in the stones at Orepuki and Riverton have also been found on float boulders in the Eglinton River and in pebbles on the East shore of Lake Te Anau. The Eglinton River flows into Lake Te Anau at a middle point along the lake’s eastern shore, having made its way there from the north-north-east: 

A “float” rock is a loose piece of rock that is not connected to an outcrop, that is, it has been removed and transported from its place of origin, especially by gravity, ice, water or people. This often makes it difficult for a geologist to identify float rocks. In relation to the terms “boulders” and “pebbles”, when it comes to the sizes of float rocks, geologists use a set of categories. One such set is as follows: A “grain” (e.g., of sand) has a diameter of 2 to 4 millimetres, a “pebble” is between 2 and 64 millimetres, a “cobble” is 64 to 256 millimetres in diameter, and a “boulder” is larger than 256 millimetres. 

5) These trace fossils were likely laid down in the Permian period. The Permian spans 47 million years from the end of the Carboniferous period about 300 million years ago to the beginning of the Triassic period about 250 million years ago. The world at the time was dominated by two continents known as Pangaea and Siberia (the latter also known as Angaraland), surrounded by a global ocean called Panthalassa. The New Zealand area was on the southeast part of Pangaea and with it moved around the southern part of the globe, including over the South Pole area.

This is how a University of Waikato website, by the Biology and Earth Sciences Departments, describes the Permian context of New Zealand and some of its local geological happenings:

By Permian times, the continents were moving even closer together than during the Carboniferous as the northern and southern supercontinents of Laurasia and Gondwana began to assemble into a single great landmass, called Pangaea. The Permian period was the final period of the Paleozoic era and is named after the province of Perm, Russia, where rocks of this age were first studied.

The global geography of the Permian included massive areas of land and water. Models indicate that the interior regions of this vast continent were probably dry, with great seasonal fluctuations, because of the lack of the moderating effect of nearby bodies of water, and that only some parts of the supercontinent received rainfall throughout the year. The ocean itself still has little known about it. There was extensive glaciation in southern parts of the landmass, shown by glacial striations on Permian rocks from what are now Africa, South America, and Antarctica, and extensive deposits of windblown soil indicate a very dry climate. However, there are indications that the climate of the Earth shifted at this time, and that glaciation decreased, as the interiors of continents became drier.

One of the most striking transitions in the evolution of life occurred when mammals evolved from one lineage of reptiles. This transition began during the Permian…

Permian rocks are widely distributed in New Zealand’s South Island and also occur in the Northland region of the North Island, where they are the oldest known rocks. In some places the deep sedimentary marine series that was laid down is up to 20 kilometres thick and one of the most complete Permian sequences preserved anywhere in the world. The biggest build up of volcanic rocks made the Takitimu Mountains near Redcliff, Waiau Valley, where the pile of tuff layers is 14 kilometres thick. Unfortunately Permian fossil outcrops are hard to find, but at Arthurton, near Gore, complete shells of Atomodesma, a bivalve, can be found. And of course a whole leaf of Glossopteris plant has been found at Productus Creek

There is no mention of the Permian trace fossils of Southland but the rocks in which they occurred, which would likely have bordered on the Waiau Valley, including the Eglinton Valley, are identified in general terms.

As Te Ara The Encyclopedia of New Zealand notes, the end of the Permian period marks earth’s largest ever extinction – two-thirds of plant and animal life died out, probably as a result of a sudden climate change.


The next Post in this Series looks at another, maybe related, explanation for the “fossilised worm cast stones” found on Gemstone Beach and the beaches of Riverton in Southland.

Six Past TumbleStone Posts of Interest to Beginning Tumble Polishers

1) What Do I Need to Start Tumble Polishing Stones Myself? And What Will It Cost Me?

This two part series sets out what a beginning tumble polisher needs and how much it will cost. The costs and details reflect that I live in New Zealand, and the prices were accurate at the time of writing, April 2018. The account aims to be fairly thorough and realistic. Part One covers: The Tumbler; The Siting of the Tumbler; Silicon Carbide Grit; Grit Storage and Tablespoon Measuring; and Disposal of Slurry. Part Two covers: Tin Oxide Polish Powder; Polish Powder Storage and Mixing; Plastic Beads and Bead Storage; Soap for Cleaning and Burnishing; Sieves and Buckets; and Miscellaneous Useful Items.

2) The Seven Stages in Tumble Polishing Stones

This at-present-incomplete Series goes through, step-by-step, the seven stages of polishing stones using a tumbler and 4lb barrel. A set of 40 beach stones collected from Riverton are used to illustrate each stage. Lots of photos show all the steps involved, often following individual stones (the stones are numbered 1 to 40). Stage One is Stone Collection (not usually included in accounts of tumble polishing).  Stage Two is tumbling the stones for about a week in 100 mesh silicon carbide grit, then tumbling them in a soap wash for a few hours. Stage Three involves one week tumbling using 220 mesh silicon carbide grit, followed by a soap wash. Stage Four is the same procedure with 320 silicon carbide grit. Stage Five involves tumbling the stones in a tin oxide “Pre-Polish” powder (five microns in size) for three to five days, followed again by a few hours soap tumble. Stage Six is the “Pro-Polish” tumble, using tin oxide powder of one micron size, for at least one week. Stage Seven is a “burnishing” tumble for a week in borax. Inspecting and sorting of the stones also take place after each Stage.

Posts in this Series to date are:

Stage One, Stone Collection, Riverton, 2-6 November 2017 – Topics include walking the beach, selecting stones, clothing, and equipment.

The Selected 40 Stones – Photos of the rough stones, dry and wet, and brief descriptions.

Stage Two, 100 Grit Tumble, 15-25 November 2017 – Step-by-step account of preparing the barrel and then emptying it after the tumble, disposal of slurry, cleaning of equipment, undertaking a soap wash afterwards, and finally determining weight loss of stones.

The Stones After 100 Grit and Their “Inspection” and “Sorting” Before Stage Three – Photos of the stones are presented after they have been through the 100 grit tumble, then an account is provided of the inspection of the stones, identifying the types of chips and holes and other “imperfections”.

Stage Three, 220 Grit Tumble, 4-13 December 2017 – This Post not only goes through the practicalities involved with the 220 grit tumble but also the inspection of the stones afterwards. 

Stage Four, 320 Grit Tumble, 10-20 March 2018 – A repeat of the steps involved in Stages Two and Three but this time with 320 silicon carbide grit.

The Stones After 320 Grit and Their “Inspection” and “Sorting” Before Stage Five – Some minor issues with a number of stones are presented, illustrated with photos.

Stage Five, Pre-Polish Tumble, 28 August to 3 September 2018 – Includes an account of preparing the tumble and the soap wash afterwards.

The Stones After Pre-Polish and Their “Inspection” and “Sorting” Before Stage Six – This Post includes photos showing all 40 stones as they looked upon initial collection from the beach at Riverton and then upon completion of Stage Five, Pre-Polish, with the stones sitting on graph paper for size comparisons. 

Stage Six, Pro-Polish Tumble, 1 October to 15 October 2018 – An account of tumbling in 1-micron Pro-Polish tin oxide powder.

Stage Seven, Borax Burnishing Tumble, 15 October to 25 October 2018 – Instead of undergoing a short soap wash after the Pro-Polish tumble, the stones are treated to at least one week’s tumbling in borax to help bring out the shine a little more. A summary of the tumbling stages and times is provided at the end of this Post.

The End Result, Stones One to Five – This Post examines how the first five of the 40 Riverton stones have emerged from the polishing process, comparing them with how they looked as rough stones fresh from the beach. Each stone is discussed and close-up photos are provided of their textures, colours and patterns.

The remaining Posts to date are How Stones Six to Ten Have Polished and The Fate of Stones 11 to 15. To Be Continued…

3) The Best Rock Tumbling Book Around – “Modern Rock Tumbling” by Steve Hart (2008)

I read the book referred to in this Post after only a couple of weeks of my own tumbling venture and found it directly relevant and immediately useful. It remains the best I have come across. It is available both as a “real” (paper) book and an e-book.

4) Sources of Detailed Instructions for Tumble Polishing Stones

This Post is a list of seven sources I have found useful for the beginning (and also for the not-so-novice) rock tumbler. They share a number of things in common but often have their own unique ideas or pieces of advice.

5) How Stones Tumble in a Rotary Tumbler

A video is referred to in this Post showing the tumbling action when a barrel is too full or not full enough. A great help in understanding why a barrel should not have too many stones in it!

6) My New Sorting Container for Stones at Different Stages of Tumble Polishing

A good way to store stones which are destined for different stages of tumbling is presented in this Post, so you can group them until you have enough for a barrel load. This also enables you to inspect stones after a tumble and feel free to set aside those that need to repeat a stage.

“Hymns to the Silence”: Recently Polished Stones from Gemstone Beach

Stones are hymns to the silence of deep time, the silence of the deep past…

Helen’s Stones, and Taking Photos of Stones – Part One: Lighting, Cropping and Straightening

In June, my sister Helen and her grandson Sam came with me on a visit to Gemstone Beach. I took 15 of Sam’s stones home with me to polish (see “Sam’s Stones“) and I also took a number of stones that Helen had collected. I used two three pound barrels to tumble their stones in 320 grit and then combined them in one four pound barrel to polish them in two grades of tin oxide. Altogether, I polished 104 stones for Helen:

In this series of Posts, I will describe how I take photos of stones and how I prepare the images for posting on TumbleStone. All the photos of stones used in the examples are from the batch I recently polished for Helen. 


My small digital camera is a Sony Cyber-shot DSC-WX500 with a 30x optical zoom lens which I find quite good at shooting in low light conditions. I am able to take reasonable close-up shots with it – it has an automatic macro-setting that is said to be best at 5 cms distance. All the photos taken by myself that are posted on this Blog, of beaches and landscapes and stones, have been taken with this camera.


The above photos of Helen’s stones were taken inside the shed where I do my tumble polishing. In fact, they were taken next to the sink where I empty the tumblers and wash the stones, away from any natural light. There is a small florescent tube light above the sink and two lights, with compact fluorescent bulbs, along the roof beam of the shed. 

Generally stones look their best in direct sunlight, their colours and patterns and grains shown in a lively manner. However, the reflections off polished stones, even  a reflection of the camera itself, can often interfere with good images. Sometimes the sun moving behind clouds makes the light conditions better and reduces reflections. Moving inside to low light conditions can eliminate reflections to a large degree (if there are no windows or other light sources nearby) but then any minor movement blurs the photo and the stone’s colour often looks more washed out. This could be overcome by mounting the camera on a tripod, but I have not yet done so. Different lighting conditions also highlight scratches and other “imperfections” in a stone in different ways.

Examples of photos of several of Helen’s stones under two different light conditions, inside the door of the shed and outside (the photos are as they came out of the camera):

The photo above left was taken inside the shed. The stone’s colour is slightly more washed-out compared to the photo above left taken outside the shed in dull sunlight. The reflections showing on the stone are different, with the light source(s) inside interfering less. The next stone is a layered grey mudstone: 

In the photo taken outside the shed (above right), the shadowed reflection of the camera and photographer can actually be seen in the stone. The two photos of the jasper stone below also show the same issues with colour and reflection. 

Below is a stone that is a little less shiny than the previous ones. The inside photo (left) is a distinctly different hue than the outside photo (right). 


I often take photos of stones after a batch has just been polished, which means I may have anywhere between 40 and 70 to record. I might photograph only a selection, maybe the most interesting ones, but there are always quite a few to do. That is one of the reasons why I take photos of the stones in my hand – I can quickly move a stone closer to the camera if I wish, I can change the lighting conditions by moving the stone around or by going outside, and I can do a number of stones in a relatively short time (though it might still take 20 minutes or more).


When I download the photos from my camera’s memory card onto my laptop, I open them in Picasa, an image organizer and image viewer for organizing and editing digital photos. Below is the “home” page when a photo is opened in Picasa. On the left is a kind of dashboard, with “Commonly needed fixes” (the spanner icon) selected. This shows options for “Crop”, “Straighten”, “Redeye” etc.

Google offered Picasa as freeware between 2004 and 2016, but then discontinued it. They replaced it with Google Photos. I am able to use Picasa still, but Google no longer offers support for it (not that I have ever needed such support).  I will describe what I do with Picasa and I assume that other photo programs or services will be able to do similar things.

In the next section of this Post, I discuss how I use the “Crop” function then I will look at the use of the “Straighten” function. My use of other Picasa functions will be examined in the second Post in this series. 


I crop photos of stones for three reasons – to balance the elements in the photo, to get a detailed enough image of the stone, and to “zoom in” very closely on the pattern, grain, colour and texture of the stone.

crop image
Cropping in Picasa
picasa home options crop
The “Crop” icon in the dashboard

Here are three examples of progressive cropping of the image of a stone (click on them to view the full photos). The first image of each of the three (far left) is the original photo, the second is the cropping to reduce the edges around the stone to frame it for viewing, the third is a “close-up” of the majority of the stone surface, with the fourth “zooming in” more closely to provide even greater detail:

The main limitation of the most-cropped image (the far right ones) is the possibility of blurring if the focus was not very good originally. This can be off-set a certain degree by using the “Sharpen” option (see next Post).


Another option provided in Picasa is to “straighten” a photo. This is particularly useful for photos of beaches where you really want the horizon line to be as close to horizontal as possible. With this photo of the Back Beach at Riverton, the original photo (below left) was on an angle, but can easily be “straightened” (below right):

Picasa provides a bar along which the cursor can move an “indicator”. Grid lines are laid over the image so it is possible to line up a horizon with one of the horizontal lines of the grid. The main limitation is that you lose part of the edge of the image as you straighten it (it “zooms in” as it straightens).

“Straighten” can also be used to change the orientation of a photo of a stone if you want to move it around less than a 45 degrees rotation (the “rotation” function is below the image, just to the left of centre):

The “rotation” functions in Picasa

It can be useful to crop an image of a stone as close as possible to its edges to highlight the stone itself. But if the photo has the stone lying at an angle to the vertical or horizontal, the “rotation” function won’t help:

The “straighten” function allows a less-than 45 degree rotation of the stone, but at the cost of a proportion of the image:

The two end results – at left is the cropped non-straightened image, at right is the cropped straightened image. The latter is closer to the perpendicular so that cropping will end up with a “closer” view of the stone:

In Post Two of this Series, I will look at the use of the “saturation” and “brighten” functions, which are crucial for the quality of the image of a stone.