Greetings fellow Foxies,
A knowledge of the underlying rocks and their history explains why the landscape and vegetation of Foxes Lair changes more over a short area than other places like Dryandra Yilliminning and Harrismith.
I guess that you need a good imagination to picture continental plates smashing together and separating again to repeatedly form and destroy supercontinents over hundreds of millions of years, and the associated earthquakes, volcanoes and mountain ranges that have formed and then weathered away.
Geology is very relevant!
 For example did you know that Darwin could be a suburb in Indonesia in 500 million years, and a visit to Bali will be a different experience, as it may be a new Mt Everest or a blob of melting rock underneath the encroaching Australasian plate?.
So here is a very simplified story!
In the wheatbelt we are on the Yilgarn Craton, a very old and stable slab of mainly granite (sandy soils) with greenstone strips (red soils, mineral fields). Since its formation (2,800 million years ago?) the craton has been stressed as it and then as part of Australia has collided with others to form supercontinents and then separated again at least five times.
These stresses caused faults in the bedrock and cracks that filled with magma from the earth’s mantle that we commonly see today as narrow lines of black rock (like dolerite) containing dark minerals that form reddish loam and clay soils (dykes).
About 2,400 million years ago a series of east/west dykes formed, with the biggest being the huge Binneringie Dyke (600 km long and up to 3km wide. The dyke aligns with the road from Quindanning to Williams and then the Williams Kondinin Road and on to Hyden and further east. Commonly driving on these main roads, I used to overestimate the amount of red soil in the district, but one soon comes into sandy soils on side roads
Narrogin and Foxes Lair sit right on this dyke that can be seen from the air as a discontinuous often double line of hills. The hills have resulted from intruded magma ‘cooking’ the surrounding rock making it more resistant to erosion, and stonier more resistant laterites formed on dolerites remaining as the surrounding landscape eroded away. The line is discontinuous because the extruded magma formed different rock types from quartz to ultramafic rock, and the dyke has since been cut by numerous younger faults and dykes.

Surrounding areas like Dryandra are mainly on granites crossed by smaller dolerite dykes (often as ridges such as on Candy Block).
Granite is actually an interesting rock. Here it formed by the collision of continental blocks. As one block slides under another it melts and huge “pools” of granite rise up and solidify as large domes like Yilliminning rock up to 2 kilometres below the surface of the plate above.
You can climb Yilliminning Rock now because over the hundreds of millions of years the overlying kilometres of bedrock have weathered and the soil washed away into the ocean.

Mind blowing stuff!
 Some light reading- Geology of Granite , Overview of Granite Outcrops
The image below shows my guesstimate of the Binneringie Dyke at Narrogin.

Last year, visiting American geologist Ray Grant noticed strange gravels that resembled South Australian fossils in the main street of Mukinbudin. The S.A. fossils called ‘clogs’ are calcified pupae cases of Leptopius species weevils (stone pigs).
Fossils have also been reported at Gracetown and the Pinnacles.
Leptopius larvae are grubs that feed on acacia roots in sand dunes before compressing an space in the soil and secreting liquid to make a case in which to pupate. After pupation the adult weevil makes a hole in the pupal case and digs its way to the surface. Over time the residual cases became cemented by a lime in the soil water.
Mukinbudin specimens are similar but chunkier and harder, and tend to have the exit hole at the end rather than the side.
I found a paper on fossilised Leptopius pupal cases in Weipa bauxite that look like those at Mukinbudin.

Greetings fellow foxies
I am sure that many of you have lain awake at night and pondered on this problem: "Why do salt lakes occur seemingly randomly along waterways, why are they round, and why do they often have dunes on one side and a steep slope on the other?.  Well ponder no more.

A good example is Taarblin Lake that is actually two interconnected lakes.

The answer is a bit complicated, but includes geology, earth movements, salt reserves in the subsoil, and long term climate variation.
Unlike most other countries, we do not have permeable sedimentary rocks under our soils. East of the Darling Fault the underlying rock is a huge slab of continental (mainly granitic) rock that makes an impermeable basement below the weathered layer. This has been fractured by faults and is crossed by lines of dark dolerite type rock that weathers to a tight red clay. These two redirect or block groundwater flow. Many Great Southern lakes started when groundwater has been forced to the surface where these structures intersect waterways.
In very dry periods winds would blow sediment out of the dry lake bed, causing it to become deeper, and producing dunes on the edge. When the lake was full, wind caused the water to swirl in a circular motion that cut away at the edges of the lake. Additionally, while a part of a supercontinent called Gondwana for hundreds of millions of years, Western Australia slowly eroded down to leave a relatively flat landscape.

There have been large climate fluctuations over the last million years or so that are associated with glaciation elsewhere in the world. In arid periods plants died and very strong north-west winds that created dunes on the south-east side of the lakes and reduced their volume. In wet periods swirling water in the lake cut into the western side of the lake causing it to move west to form a cliff.
Lake Taarblin was considerably larger when the climate was wetter 3000-4000 years ago, but the eastern side has since been infilled by dunes and interdunal salt pans.
When more water entered the soil than plants could use, salt was brought to the surface in groundwater causing salt patches. This is happening now after clearing bush for farm land, but it has also happened naturally in the past. Interestingly first Europeans in the district discovered that the existing lakes were mostly fresh, but did not fill as much as today.

You may have noticed that lakeside dunes are mostly sandy in the Western wheatbelt, but loamy with lime nodules in dryer areas. The reason for this is that lakes in the east tended to be dry and saline in arid periods with dunes created from the saline lake floor, whereas western lakes were full more often with sand washing in with the water.
You can tell the difference from the dunal vegetation. Acorn banksia (Banksia prionotes) and woody pear (Xylomelum angustifolium only occur on wind deposited sand.

However red morrel (Eucalyptus longicornis),  Kondinin blackbutt (E. kondininensis) and other salt tolerant eucalypts characterise the salty lakeside loams.

To complicate things a bit more, there is another factor affecting the location of salt lakes – major ground movement.
This is the story: When Australia finally separated from India on the west and Antarctica to the south, stress in the underlying basement rock caused two things to happen.

1. Great rivers used to flow south from as far north as Beacon in deep canyons to the south coast. The Antarctica separation caused the rise of a low east west ridge near the south coast called the Jarrahwood Axis that tilted much of southern WA down to the north and reversed the flow of these rivers. Resulting sluggish valleys with little slope filled up leaving a chain of lakes that only flow in a very wet year all the way to the Salt River past Quairading then the Avon to Perth.
2. The Salt River and other rivers like the Beaufort and rivers further north, were also large active rivers that flowed to the coast when India was gradually separating from WA. After the separation the Darling Range gradually rose upwards and blocked these rivers, causing them to back up as huge lakes that became the source for extensive sandplains to their south and east. A prime example is the Yenyenning lake system where the Salt River was diverted north to the Avon River.
These earth movements in conjunction with climate variation has resulted in large areas of aeolian soil in the wheatbelt. These include the Watheroo, Meckering/Cunderdin, and Corrigin/Quairading sandplains, and morrel blackbutt loams in the Lakes District.

Greetings fellow Foxies,

                            Earlier this year a colleague asked me if I knew what caused hollow ironstone pipes that were exposed in a gravel pit on private property south-east of Quairading. The pipes start about 2 metres below the surface and continue into the gravelly clay base of the pit. Equally amazing is the location on a granite/dolerite ridge.
I was pretty sure that it is a laterite formed from sand and checked out the site with Dr Bill Verboom.
Bill’s ground-breaking research has revolutionised the understanding of soil formation, and underlies much of the following.

This raises some questions
·         How did a sand dune form on a ridge in the wheatbelt?
·         How did the sand turn into gravel and what causes the ironstone pipes?

A clue to the sand deposit lies in the large salt lake chain (The “Salt River”) to the west of the gravel pit. Millions of years ago this was a mighty river that flowed to the Helena River in Perth. Gradually the river was blocked as the Darling Range was uplifted, causing the river to back up (forming a lake?) until it was diverted north in its present course as the south branch of the Avon River. The climate was also gradually changing and becoming more variable with alternating wet and dry cycles, particularly in the last hundred thousand years. During extended droughts strong winds blew sand from the dry river/lake beds to form aeolian sand deposits (present Banksia prionotes yellow sand deposits).
We know that these are aeolian deposits because of the uniform sand grain size.

A clue to the gravel formation is the vegetation at the top of the pit face, which comprises Allocasuarina campestris (a tamma) and a grevillea species.
I  have briefly described how these plants and associated bacteria create gravel soils, and  provided more information in these references.
This spot is more complicated than most in being an old sand deposit over reddish clay formed from dolerite. My guess is that iron, aluminium and silica released by special plant roots has been converted into gravels, and being pumped up from mineral rich depth by tap roots has also been deposited around the roots to form the ironstone pipes. Because the gravel is quite loose due to little clay being present in the sand, it has flowed away from the pipes when the pit was excavated.
Thumbnails below show detailed images of the pipes. Click each to expand the image. You will notice that despite being tough rocks they are just fine sand that has been cemented together by aluminium (white) and iron (yellow/orange/red) oxides and silica (not obvious).

Ain’t nature wonderful?