November 2021 – TumbleStone

“Y” is for “Yellow Beach Stone from Kaikoura Coast” and “Z” is for “Zoomorphic Shape in Stone”

T is for Timaru Today

U is for Unusual Variations of Trace Fossil Stones

V is for >>>>>>

W is for Ward Beach ZoophycosCross in a Stone

X is for X-Figures When Veins Cross in a Stone

The following are my final Posts in the weekly alphabetical series of a Facebook Group I belong to, “New Zealand Lapidary, Rocks, Minerals, Fossils”. The first Posts in this Series can be found here. The Series Index is here.

“Y” is for “Yellow Beach Stone from Kaikoura Coast” – I found this small stone in August 2020, just south of the Waima (Ure) River mouth, about 70 kms north of Kaikoura. The creamy yellow pastel colour in it is complemented nicely by the blue.

One side of the small beach stone, when found.

Other side of the stone.

Page 92 of R.L. Bonewitz (2008), “Rocks & Minerals: The Definitive Visual Guide”.

It might be limestone, but I am unsure – the trace fossil trail in it means it is certainly sedimentary. Colour is an important characteristic of stones – it is often what makes them attractive, and it is what can catch the fossicker’s eye. Colour variations, contrasts and patterns are all significant. But when it comes to identifying a stone, colour can often be unhelpful or even misleading. As R.L. Bonewitz writes in his book “Rocks & Minerals: The Definitive Visual Guide” (2008), page 92 (see photo below): “Some minerals have characteristic colours and others do not… As few as three or four atoms per million can absorb enough of certain parts of the visible light spectrum to give colour to a mineral. [Furthermore] the colour produced by a particular trace element varies according to the mineral it inhabits.” One good online introduction to colour in stones is www.minerals.net/resource/property/color.aspx.

“Z” is for “Zoomorphic Shape in Stone” – “Zoomorphism” means “in the shape of an animal”. Applied to stones, it could mean a stone in the shape of an animal. Or it could mean a stone that contains an animal-like shape, either in veins or blobs within the stone. This small beach agate was found near Kakanui in February this year. It contains some light-yellow inclusions, outlined in black, some of which could be imagined to make up a simplified giraffe form.

This is the end of this Series. The full Index for the Series can be found here.

“W” is for “Ward Beach Zoophycos” and “X” is for “X-Figures When Veins Cross in a Stone”

R is for Riverton Rocks Red Rock

S is for Slope Point Stone

T is for Timaru Today

U is for Unusual Variations of Trace Fossil Stones

V is for >>>>>>

The following are my Posts for “W” and “X” in the weekly alphabetical series of a Facebook Group I belong to, “New Zealand Lapidary, Rocks, Minerals, Fossils”. The first Posts in this Series can be found here. The Series Index is here.

“W” is for “Ward Beach Zoophycos” – This stone contains a trace fossil, called zoophycos, and similar stones can be found especially along the Kaikoura coast. As noted in “A Photographic Guide to Fossils of New Zealand”, Ward Beach is famous for this type of trace fossil stone, of which there many variations.

Zoophycos stone from Ward Beach.

Page 64 in “A Photographic Guide to Fossils of New Zealand”

Ward Beach is about six kilometres off the main road east from the small village of Ward in the Flaxbourne District, 82 kilometres north of Kaikoura and 45 kilometres south of Blenheim. The Flaxbourne River reaches the coast at Ward Beach, which is set among spectacular scenery – high hills with steep slopes and a coastline with interesting rock formations. The Ward Beach boulders (concretions) are not far from the car park (maybe 10 minutes’ walk north). The beach was uplifted by the 2016 Kaikoura earthquake, unveiling the boulders.

The car park is near the centre of this stretch of beach. The boulders are a bit further north along the beach.

My little red car can be seen in the car park here. Looking from the south.

Looking from the north.

The beach in front of the car park, at low tide.

Some of the Ward Beach boulders.

Ward Beach stones.

Another Ward Beach zoophycos stone.

The best part of the beach for stones is immediately in front of the car park, though it can be steep as it gets closer to the water and the incoming waves can be dangerous.

“X” is for “X-Figures When Veins Cross in a Stone” – This tumble-polished Birdlings Flat quartzite contains many veins, some very fine, others less so. When veins cross, “X”s are discernable. I have highlighted two of the many in this stone.

Polished Birdlings Flat quartzite.

“U” is for “Unusual Variations of Trace Fossil Stones” and “V” is for “The Chevron Shape of Trace Fossils”

P is for Planet in a Pebble

Q is for Quartzite Stone from Kakanui

R is for Riverton Rocks Red Rock

S is for Slope Point Stone

T is for Timaru Today

The following are my Posts for “U” and “V” in the weekly alphabetical series of a Facebook Group I belong to, “New Zealand Lapidary, Rocks, Minerals, Fossils”. The first Posts in this Series can be found here. The Series Index is here.

“U” is for “Unusual Variations of Trace Fossil Stones” – These four trace fossil stones (also known as “fossil worm cast” stones) were all found on Gemstone Beach this morning [21 September 2021]. The waves were coming unusually high up the beach so my fossicking was restricted to just a couple of hundred metres in front of the car park. The first two stones:

“Unusual” because of the sheer number of small trace fossils in the stone.

“Unusual” because of the raised trace fossil. The trace is more resistant to eroding by the sea and sand, due to being of a harder material than the rest of the stone.

Stones three and four:

“Unusual” because of the large “blobby” light-coloured trace fossil.

“Unusual” because of the light colour of the stone and trace fossil – you might need to look carefully to see it.

The waves sweeping high up Gemstone Beach this morning, just before high tide.

“V” is for “<<<<<” – the chevron shape of some of the trace fossils (also known in the south as “fossil worm casts”) to be found in argillite. A chevron is an inverted V-shaped pattern (or a series of Vs in a line of any orientation). Its first use culturally can be traced back to Bronze Age pottery designs in Knossos, Crete. The word “chevron” is French and derives its meaning from the Latin word “caprio”, or rafter, due to its resemblance to building rafters. Chevron designs are often used on badges or insignia used by military or law enforcement to indicate rank or length of service. Chevron trace fossil shapes are often viewed in the international trace fossil literature to be indicative of the “protovirgularia” trace, and usually not attributed to the activity of worms. The diagram below is from a 2010 article on protovirgularia found in Patagonia, Argentina, published in the “Journal of Paleontology”. In this article, the authors state: “Chevronate structures assigned to Protovirgularia are best understood in terms of a push-and-pull mechanism of a split-foot mollusk, either a protobranch bivalve or a scaphopod: the penetration and the terminal anchors working sequentially. The separation between successive chevrons indicates the distance that the shell moved towards the foot during protraction of the pedal retractors. The open side of the chevrons indicates the direction of locomotion” (pages 732-733 in this academic article in the Journal of Paleontology.) Photos below are of trace fossil stones from Gemstone Beach (Southland) that I have collected over the past four to five years.

Source: 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?fbclid=IwAR0t5u3JbTRWA06ED9FooRfoIyLxgNJA0RShF9MGYKaXiKmzop4z4Cj8Vgg

Source: http://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?fbclid=IwAR0t5u3JbTRWA06ED9FooRfoIyLxgNJA0RShF9MGYKaXiKmzop4z4Cj8Vgg

The next Post in this Series can be found here.

Kakanui Fossilised Sea Floor Stones – Only 400 Grit Tumble

Here are four Kakanui stones that have been tumbled only in 400 grit. I have discovered that tumbling them further does not improve them. As it is, they come out of the 400 tumble smooth and waxy-feeling, and showing clearly the often-tiny fossils within them. I have previously referred to them as fossilised sea floor – they are a kind of limestone.

The four fossil sea floor stones from Kakanui after 400 tumble.

The beach just north of Kakanui village where I found these stones.

Another view of the Kakanui beach.

Stone 1.

Stone 2.

Stone 3.

Stone 4.

When found on the beach, these stones are often unremarkable, being whitish, sometimes showing some darker grains within them, sometimes hinting at the small fossils in them, often feeling grainy and powdery. Some of them have holes in them, some of them have no fossils. But many of them turn out to be very intriguing. About 900 metres down the beach from where I park my car (at the end of Seadown Road), there are usually some rocks poking through the sand that are made of the same stuff, though I have not seen the tiny fossils in them that these stones contain.

Fossil sea floor rocks 900 metres down the beach.

Examples of “rough” fossil sea floor stones from Kakanui, as found.

I tumbled a batch of these stones in 400 grit in a 3lb barrel recently. I did not open the barrel until after 11 days of tumbling. Inside was a thick fine-grained slurry and I worried initially that the stones might have been worn down too small. It turned out they were still of a good size – I have usually tumbled them only for about 7 days, and in future will restrict them to 6 to 7 days in the barrel. These four stones were among the most interesting in that batch – the tumbling revealed much more than was able to been seen in the “rough” stones. Here are the first two stones: