Greetings fellow Foxies,
I was blown away to find an outcrop of banded ironstone on a gravel ridge on the Banksia Walk. It is only a small outcrop but was a great surprise because banded ironstones are ancient deep-water sediments that are much older than the underlying granites in the district.
I consulted my geologist colleague Jefferson Harris who was equally blown away but offered the following amazing explanation. It is a long story that involves cataclysmic events over billions of years.
​The story starts somewhere around three billion (3000,000,000) years ago when there were ‘islands’ of continental rock in a world-wide ocean. At this time there was little oxygen in the atmosphere or the water that contained dissolved iron and other minerals coming from ocean vents.
In deep still-water basins around the islands, silica (an often-tinted type of quartz) was slowly deposited. Life at this time included early stromatolites (like those in Shark Bay) that gradually released oxygen.
When this oxygen reached a certain level, it combined with dissolved iron that settled out as a dark iron-rich layer on the sea floor. The oxygen depleted water then accumulated more dissolved iron.
As oxygen content of the water fluctuated, alternating quartz and iron-rich sediments accumulated as thick layers that became banded ironstone formations in areas like the Hammersley Ranges.

Now to explain how older banded ironstone came to overlay younger granite: -
As the islands and their associated deposits collided, the edge of one was forced under the other in a process called subduction. The sinking edge melted as it continued down into the very hot underlying mantle of the earth. This created huge molten blobs of granite that rose through the mantle until it met overlying cooler rock. (which in this case contained banded ironstone).
As the molten granite continued upwards its heat caused the overlying rock to crack and sink down into the lighter granite and be incorporated into it.
The island underlying Narrogin (the Boddington terrane) joined others to form by a huge stable slab of continental granite-type rock called the Yilgarn Craton that underlies most of the agricultural area and goldfields. This has remained relatively stable, and the exposed rocks slowly weathered to soil that was washed into the ocean. The land surface of the Narrogin area became lower until granite containing embedded banded ironstone was exposed on the surface
 A mere hundred million years ago the proteaceae family developed the ability to extract phosphorus from poor soils that led to the formation of lateritic soil from soils derived from weathered granite.
To simplify a long story, we now have banded ironstone embedded in laterite!

​Greetings fellow Foxies,
 I love climbing and understanding rocks (my wife thinks that there is mountain goat in my ancestry).
In the process of producing a Boyagin Rock brochure I climbed over and around it and compared it with our other great rock tourist destination, Yilliminning Rock. Both are inselbergs that outcrop from underlying granite basement rock that welled up when two older slabs of continental rock crashed into each other about two thousand seven hundred million (2,700,000,000) years ago. At the time volcanos erupted and a huge alpine mountain range similar to today’s Himalayas was formed. Over great time this bit of rock joined with others to form Australia and the supercontinent Gondwana, that joined more to form the global supercontinent Pangea, that then split up (greatly simplified). Very slowly the mountain range weathered and washed away.
Another mind-blowing statistic is that Yilliminning and Boyagin rocks were once part of magma chambers 5 to 7 kilometres below the ground surface. These have been exposed over eons as the overlying material was removed.
 
In the agricultural area, features like ridges, cracks and waterways tend to follow straight lines that may suddenly change from one direction to another. Our soils and the depth to crystalline bedrock are shallower than many other parts of the world. Surface features often reflect faults, intrusions and other changes in the mainly granite basement. Lines frequently trend northwest- south east, northeast -southwest, east-west, and north-south.
 
There are distinct differences between the two rocks.
Yilliminning Rock is more typical as a large granite dome arising from a gently undulating landscape.

​The Boyagin landscape is much hillier, and the rock itself is more variable. It is one of two adjoining large rocks project from the eastern side of a lateritic upland plain.
In the early morning, variations in the texture of Boyagin Rock granite can be seen in strange shapes where there has been uneven weathering of the rock. Look closely and you can see lines and mini ‘craters’ and lumpy spots on the otherwise smooth granite. 

​A look on a map shows that uplands and rivers in the Brookton area commonly trend north-south up to beyond the Avon Valley.

​An explanation goes back about 95 million years when India was once attached to, but slowly separating from WA. Brookton and surrounds were part of a plain with west-flowing rivers carrying sediment
into a rift valley that is now the Swan Coastal Plain (Perth – Bunbury etc.)
 
83 million years ago India finally separated from western WA and drifted north to crash into Asia.
With the weight of the Indian block removed, a line east of the Darling Fault from about Carnamah to the south coast bulged upwards to create the Darling Range. The land rose about 250 metres and was accompanied by other parallel downward and upward folds in the ground to its east.
 
These changes in slope completely blocked the old east-west flowing rivers and the blocked water ran down a new valley south from Dalwallinu (Mortlock North branch), and North from Pingelly (Avon South branch) into the Swan River.
The newly created Boyagin Creek then exposed Boyagin Rock.
​General north- south river systems and lines of ridges in the Darling Range can be seen on the before and after diagrams

​When I investigated the southwest base of Boyagin Rock I was surprised to see what looks like a quite recent north west-south east fault in the granite that had been exposed in a creek. 

As it turns out, generally east of Brookton is a localised earth movement hotspot in the southwest seismic zone (remember the Meckering earthquake?).
The Darling Range may also still be slowly rising so the old rocks may still be rocking. Of course the Wagyl also had a part to play.
 Click this link for a visual exploration of the rock.
Next time you climb Boyagin Rock take a good look around and be grateful for this true rock of ages.

​Greetings fellow Foxies,
Despite an exceptionally dry summer and autumn, we have had over 90mm of rain since mid June. If it all soaked in it would wet the soil to at least 2.5 metres. There has been relatively little runoff and I was gobsmacked, and very concerned to find dry soil within 5cm when digging side-drains on a range of soil types on walking trails to reduce erosion. These soils are massively water-repellent.

If the water largely didn’t run away, where did it go? Many of our native plants have excellent strategies for channelling water down their roots, and an experiment I did some years ago showed the importance of obstructing surface water flow to allow time for water to overcome the water repellence. The image below shows a section of water repellent soil where a racehorse goanna had been burrowing for insects in an old root channel. Note how moisture has wet the soil to depth around the root channel.

​I read this great article about the importance of woylies in the regeneration of sandalwood and native poisons. No doubt emus were also important.
​
Woylies and emus have gone from most of our reserves with the only burrowing animals being rabbits, reptiles and  echidnas. This is having a massive impact. Over time as plants die leaving bare ground and roots rot away there is less chance that new plants will replace them unless conditions change.

I commented on  irreversible changes in small reserves previously, and feel sad about the ongoing loss of nesting trees.
When entering Foxes Lair from opposite the caravan park, one can see poorer shrub and wildflower growth on the left side that hasn’t been burnt for over 50 years on the left, compared to vibrant growth on the right where an arsonist burnt about a third of the reserve.
That fire was a real revelation for me, as it triggered orchids I hadn’t previously seen and rejuvenated small bird life such as  quail that hide in dense undergrowth.
The arsonist had several goes in Foxes Lair After a small attempt I noticed a smouldering front moving through the soil under marri that burnt the water repellent organic surface layer to a depth of 3cm, and after the arsonist’s finale the fire continued to burn along underground tree roots for about 3 weeks (lesson here don’t walk through burnt country soon after a fire – your foot can plunge into underground burning root). The images below shows the difference burning made on the Valley Walk.

​What can be realistically done by volunteers and local government in small reserves?
 
Over time I have developed the following achievable strategies in Foxes Lair.

• Proper low intensity mosaic burns, with raking around big standing dead trees that are vital nesting spots. I developed a 10 plus year interval burning program for blocks in the reserve (no luck with implementation so far).
•  When pruning is required or trees fall across tracks etc. prunings are placed on bare areas to help trap water (amazing how quickly the leaves disappear).
• Dig small side drains at short intervals along trails and roads to return water to the bush more evenly.
• Spread soil from these side drains on to bare areas to introduce and retain seed and help water infiltration.
• Control weeds (so many).
• At the rate that large nesting trees are falling over, I reckon that nesting boxes will be needed one day.

I still remember being appalled at the lack of bird diversity when I travelled overland from India to Turkey a lifetime ago. Just sparrows,pigeons, crows and vultures!
​ I would hate Australia to go down that route.

Greetings fellow Foxies,
Local history accounts and observations in many reserves have made me realise that our so-called ‘natural bush’ is in fact quite modified.
 
Native animal extinction effects
Over a decade ago I was involved in the closure of redundant roads, and creating new walk trails in Foxes Lair. Gravelly areas regenerated quickly, but others soil areas took many years for plant colonisation. Initially I thought that phosphate contained in gravels was the key but an experiment I carried out by digging holes and observing wetting patterns pointed to water repellence. I also noticed that water repellence caused water erosion on new tracks I created in even the light rains.
I couldn’t understand the benefit of this in the natural landscape until I was reading early settlers’ accounts while doing research for my Vanishing Farms series. We have removed vital links in our natural ecology.
The first link is burrowing animals that used to bury seeds and provide depressions that collect water for seed germination.
“(The Blight family) experienced great difficulty in growing crops owing to the large number of Boodie rats (bandicoots) that devoured the crop in the early stage of growth” (Wolwolling Reflections page 73)
 
Fire effects
Our bush depends on fire (about every 20 years in this district as a rule of thumb), for the maintenance of an ecologically diverse landscape, and fires were not uncommon on the uplands before farming.
“In the valleys of the gravel hills, a summer fire was an awe inspiring sight. The scrub and litter of years swept by the suction of this inferno of rising heat, flames often rose 50 or 100 feet scattering burning twigs and leaves half a mile in the wind. After the fire the desolation was complete, but when the rains came, the strengthened rejuvenation was unbelievable. Later when the clearing and had brought the grass and stubble of crops we became more fire conscious” (The Way Through page 35).
Hot fire removed water repellence and any competition for new seedlings.
Our scattered reserves need careful burning. A single large hot burn is disastrous because animals in the reserve can no longer escape to another place and if wiped out by fire, and there is no recruitment from neighboring bush. On the other hand, most reserves I see now have upland areas choked with dead timber waiting for the next lightning strike. I gather that local fire brigades do not have the resources or training or time to burn bush areas, so the opportunity for planned burning in reserves (apart from those administered by Parks and Wildlife) is miniscule.
 
Overgrazing
I got a shock when I found a fenced enclosure on a gravelly upland plain at East Yornaning reserve recently.  I had previously thought that the sparse wandoo/sheoak/grass tree was normal, but there larger and several more understorey species inside the enclosure below indicates otherwise.
Overgrazing by the 1930s to 1950s rabbit plague can’t be blamed as this spot was fenced long after that and Gastrolobium poison peas would have killed grazing livestock. From the large kangaroos bounding around this reserve I can only conclude that there are too many of them here.

On reflection, this isn’t unexpected as they have an amazing breeding rate in the right conditions and can only be culled after obtaining a licence (which only occurs when there is evidence of crop damage).
History tells me that dingos were common here when settlers first arrived and were around until the 1920s, so these kangaroos now have no natural predators (apart from cars on the road!).
Unfortunately most humans have lost contact with nature, and do not realise that evolution is driven by competition, where most young die annually by predation to avoid overpopulation, and nature corrects any imbalance in population in often nasty ways. A couple of times kangaroos in Foxes Lair were blinded by a virus-borne virus that spreads when populations increase. They would have starved to death if not euthanized. Similarly, the enormous breeding capacity of our marsupials is driven by them taking advantage of good seasons after much of the population had died during droughts
 
Human rulers prefer to use war to cull the young, weak, and poor.
 
Recently I noticed that Commodine Nature Reserve is notable for interestingly trimmed grass trees that reminded me of a Ring-neck parrot plague decades ago: Then it was so bad that they killed plants.
I am thinking of putting a few small enclosures in Foxes lair to monitor the difference.
 
To quote guru Greg Durell, “Natural is what you see on the day”