The Yellow Sands Formation outcrops along a roughly north-south line to the east of Durham (thin yellow areas fig 1). At exposure it displays as a soft, minimally cemented, yellow sand. It is dated as early to middle Permian. The sands are of aeolian origin, having formed when the crust of the future Britain was located within the heart of Pangaea at a location around 10° north of the equator. The climate was arid, the area being within the equivalent of today’s northern hemisphere trade wind belt.

Examination of the Yellow Sands Formation at several exposures, combined with data from numerous boreholes, and no doubt the many mine shafts that were sunk, penetrating the Yellow Sands to reach the coal bearing Carboniferous rocks below, has allowed their 3-dimensional morphology to be determined.

As illustrated by fig 2, this takes the form of long ridges of sand, 1.5-3km wide and approximately 30m high. The ridges having a northeast to southwest orientation [1](Chintz and Clemmensen, 1993 ). Turning to present-day environments for an analogue, one is to be found in the deserts of the Yemen, where the long sand ridges are called Draa – from the Arabic word for arm. The interdraa areas have only shallow sand and often a gravel deposit.

Fig 2. Based on map from Clemmensen, 1989

To record the Yellow Sands exposures in the faces of the McCall Field House Sand Pit quarry whilst they remain well displayed. The quarry has ceased operation for sand extraction and is now a landfill site. In the coming years it is inevitable the exposure will degrade, from natural weathering, vegetation growth and probable burial from infill.

The exposures were recorded using a drone to create a 2D grid of 80% overlapping high resolution images, orientated perpendicular to the quarry face. Fig 4a is a sample of one of these images, reduced in size here for web delivery.

Video traverses of the faces were also made. These images have been used in the creation of the following diagrams.  They will also be used to produce a 3D model of the quarry faces, employing the technique of photogrammetry. The model will be made available here.

In the account of the Field House Sand Pit exposure, given in Clemmensen (1989), he describes a far wall orientated northwest-southeast, nearly perpendicular to the draa ridge, with two abutting walls nearly parallel to the ridge. The description is from a time when the quarry was being actively extended. The current (2025) exposure is clearly different.

Fig 7 above, overlay highlights the cross-bedding visible in the ‘west’ and ‘north’ faces of the quarry. Note, faces are effectively at right-angles to each other.

In fig 8 below, these images have been fused with perspective applied to reflect their oblique relationship. The blue arrows depict wind direction at the time of sand deposition. based on the dip angle (apparent dip as we are not necessarily seeing the full dip in these 2D slices) of the cross beds.

The principle directions are made clearer by displaying them on the near vertical view of the quarry faces.

From this the flow along the face closest to the draa SW-NE trend is potentially bimodal, with an approximate north origin wind on the lower beds and a reversed southerly origin in the upper beds. In the more oblique to the draa orientation ‘north’ face, we see evidence of an approxiate flow from the east. The bedding in this face often displays a more tabular form, which implies we are observing cross-beds end on – see fig 9.

How do these findings compare with the data published in [1]Chrintz and Clemmensen? In their paper the authors describe a bimodal wind pattern, one component towards the NW or N in winter alternating with a summer SE to E wind. The two dominant directions found for the ‘west’ face are broadly in agreement with this. However, nature is far more complex and diverse and their paper discusses superimposition of dunes following a sinuous flow along the draa ridges (see fig 11). At the exposures discussed in the paper, they distinguish between bedding related to the draa from that of the superimposed dunes. However, this distinction is not explicitly presented in the case of Field House Sand Pit. It is therefore possible, many of the cross-beds visible in the quarry may be associated with dunes superimposed on the draa and therefore yielding giving a wide scatter of potential wind directions. Chrintz and Clemmensen found the cross beds of the dunes structures gave a bimodal pattern, one mode. towards the NW (313°), the other mode towards the S-SE (171°) – angles given clockwise from N (zero°).

It is well worth using Google Earth to examine the extraordinary range of sand body forms in the Yemen and other deserts. These range from the linear ridges of the draa, through to grids of interconnected barchan (crescent shaped) dunes, one form often transitioning to the other.

Continuing southward along the ‘west’ face at Field House Sand Pit you encounter this smaller exposure (fig 12), separated from the main face by slipped sand and vegetation. In a face about 4 metres high, it displays two very clear and differently orienated sets of cross-beds. One (the upper set) indicating deposition by wind originating from a roughly southerly direction. The lower set deposited by wind from a northerly source.

As good a site as Field House Sand Pit is to examine the Yellow Sands, it is a dangerous working land fill and you will need to seek permission to visit. The following locations are open for access and provide good, contrasting exposures, of the formation.

Fig 13. Dashed green line shows route of walk from the free car park at the Locomotion museum to the quarry.

Fig 15. Formations exposed in the quarry faces – click image to enlarge.

The Yellow Sands Formation is much reduced in thickness, compared with that at Field House Sand Pit. The reason? The location was interdraa, and so lying in the shallow, often gravelly channel, between draa ridges, where little sand was deposited.

NOTE: Middridge is a SSSI site (due to the fossils the Marl Slate Frm has yielded) and so the rock faces should not be hammered. Take only photos and collect any samples from the scree.

Fig 18. A natural cliff beside the River Wear in Sunderland. Exposures of the Yellow Sands Formation are visible at the base of what is effectively a cross-section through a Permian reef, along with a surface along which a massive submarine slide occured back in the Permian – but that is all part of another story! A scamble up one of the steep paths, provides access to a platform along the level of the Yellow Sands. Free parking beside the river.

Fig 20. Five metre high outcrop eastern end of Claxheugh Rock

Fig 22. Tynemouth Castle sits atop an outcrop of Permian Raisby Formation, below which is a thin layer of the Marl Slate Formation, followed by the Yellow Sands which in turn sit on an eroded surface (unconformity – shown by dotted line) of Carboniferous rocks.

Access to the foreshore via  North Pier may still be fenced off, due to damage by Storm Babet in October 2023. Alternately, the exposure can be reached by clambering over rocks at low tide from King Edward’s Bay (Short Sands). In the bay, the southerly cliff face, exposes Yellow Sands over Carboniferous rocks, but the contact is poorly exposed and  located high on the cliff face.

Fig 23 is a close-up of the unconformity between the Carboniferous rocks and the Permian Yellow Sands. The unconformity marks a terrestrial eroded surface exposed for many millions of years, before sands began deposition, first as barchan dunes then building into draa (formation process discussed in [2]). The Carboniferous sandstones below this  regionally widespread unconformity are often stained red, due to iron mineral oxidation during the period of surface exposure. The Yellow Sands themselves were also most likely red initially, the yellow colour developing much later after deposition.

Fig 24. Cliffs of Yellow Sands at Cullercoates Bay. Best visited when the tide is low.

Fig 25. veins criss-cross the surface of the Yellow Sands in the cliffs. This is due to the sandstone becoming better cemented due to later precipitation of minerals.from solutions passing through the rock. In the exposure (fig 28) the mineral is baryte..

The Yellow Sands at Smuggler’s Cave are overlain by deposits left by the last Ice Age, around 10,000 years ago.
At low tide on the foreshore it is possible to see the underlying Carboniferous rocks and the Marl Slate Formation above the Yellow Sands – seaweed and tide permitting!

Fig 27. North Point seen from Long Sands Cullercoates

A fault (fig 28), known as the Ninety Fathom Fault runs through the southern side of Cullercoates Bay. The fault has a downward displacement on its northern side of 150 metres. Fractured rock (fault breccia) is visible along the plane of the fault. The adjacent Carboniferous rocks, include an exposure of the Hutton Coal seam. Traces of Carboniferous plants can be found in the sediments below the seam.

Fig 30. Sample of the Yellow Sands Formation taken from 1 metre up the face of the smaller southern exposure (///agreed.warns.harder) at Field House Sand Pit quarry. The quartz grains are well-sorted, well-rounded with frosted faces. All indicative of aeolian transportion, with frequent collisions between the grains producing the rounded grains and frosted faces. Details of intergranular minerals and origin of the distinctive yellow colour (at depth the rock is grey) are discussed in [2].

The Yellow Sands have a very high porosity. Consequently, the rock is a natural aquifer and beneath the North Sea, where impervious caping rock is present, acts as  a major hydrocarbon and gas reservoir.

Provenance of the Yellow Sands

The Wesphalian Carboniferous rocks which underlie the Yellow Sands Formation, are predominantly sandstones and therefore a possible source of the sand. Following uplift in the Variscan Orogeny, the Carboniferous rocks underwent extensive erosion duing the late Carboniferous and early Permian, forming the eroded desert floor upon which the Yellow Sands began deposition. There are some complications to  this simple picture and other sources of sediment are possible candidates.  A detailed discussion can be found in [2].