Stay-at-Home Day Twenty-One, Wednesday 15 April 2020: Stone Twenty-One

Stone Twenty.

Stone Nineteen.

Stone Eighteen.

Stone Seventeen.

Stone Sixteen.

At the end of Week Three, Stone Twenty-One is another fossil worm cast stone. This stone is a medium-green argillite, the trace fossils being light green. Such a colour combination is the most common for worm cast stones at Gemstone Beach and Riverton. Argillite is a hardened, slightly recrystallised, mudstone. The darker in colour it is, the finer grained it is. 

Stone Twenty-One.

Stone Twenty-One.

Stone Twenty-One.

One side of Stone Twenty-One.

Some of the traces on this stone are chevron shaped.

Stone Twenty-One, chevron shaped trace fossil on bottom of stone

Stone Twenty-One, semi-chevron shaped trace fossil.

Stone Twenty-One up-close.

Stone Twenty-One up-close.

What is unusual about this stone is that some of the fossil casts or trails appear elongated, maybe stretched from the pressures that turned sediment to rock over thousands of years. 

Stone Twenty-One, elongated trace shape.

Stone Twenty-One, elongated trace shape.

Stone Twenty-One, elongated trace shape.

This is the fourth worm cast stone featured in Week Three of Stay-at-Home:

One side of Stone Twenty-One.

Stone Nineteen.

Stone Seventeen.

Stone Fifteen.

The next Post in this Series is Stay-at-Home Week Three, Stone of the Week.

Author: tumblestoneblog

Retired Academic, male, living in the New Zealand countryside near Whanganui with his wife as well as Jasper the dog, Fluffy the cat, Dancer and Penny, the horses, and a shed half-full of stones. Email john.tumblestone@gmail.com. View all posts by tumblestoneblog