A cold day with raging breakers pounding the shore. The tide was high, too high to walk the beach and observe the geological strata. However, the Permian Yellow Sand exposure is easily seen in the picture below. It ismore resistant to erosion than the shales and mudstones surrounding it. The yellow colour is due to Limonite, an iron ore derived from veins of Iron Pyrites. The lemon-ochre coloured powder can be used as a cosmetic or as a pigment.

This explanation board confused me since it refers to the 90 Fathom Dyke. It is in fact a fault but was called a Dyke or slip-dyke locally by the mining industry. The 90 fathom Fault is a continuation of the Stubblick Fault which forms the Northern edge of the Alston Block and runs East to West. No one is sure exactly where the Iapetus suture is situated because it is at a great depth. It was created when two ancient land masses collided and the Iapetus Ocean closed. It is likely that many E-W trending faults in Southern Scotland and the Stubblick fault formed during the collision.

The 90 Fathom fault can be seen by the side of the cliff as the land dips in the picture below. The strata to the North are downthrown by 150m to bring the Hutton coal seams of the Carboniferous age in contact with Permian Yellow Sand. All this, and the cave showing differential erosion is better explored at low tide.

We did not disturb the birds on the beach margin. Redshanks (Tringa totanus) were busy sprucing up or feeding. Redshanks hunt for insects, earthworms, molluscs and crustaceans by probing their bills into soil and mud. We saw others on the grassy topped cliffs doing this. Unfortunately, the outcrop of the Raisby formation and Marl Slate could not be seen on this visit.

There are three species of birds in the photo below. Ringed Plover (Charadrius hiaticula), the dumpy birds in the middle, Black Headed gull (Chroicocephalus ridibundus) at the top of pier and Oyster catchers(Haematopus ostralegus) in their familiar black and white plumage. They had paler legs and beaks than usual so perhaps they were juveniles. Others were feeding on the grass above; although they are specialist cockle/mussel  feeders, worms are also eaten.

I was surprised by the number of Buck’s Horn Plantains (Plantago coronopus) scrambling over the channel Sandstone. They have tiny pits on their hairy leaves that eliminate excess water and salts.

Where there are rocks, lichen are usually to be found. Caloplaca maritima has orange waxy fruiting bodies, the other creamy coloured one is some species of Lecanora, probably L actophila.

Knotted or Egg Wrack (Ascophylum nodosum) was photographed after being picked up from the beach. An alga of sheltered rocky shores it forms one air bladder per year. This piece had been broken off, so could not be aged.

This seaweed, mostly kelp, had been washed up into a tide-wrack by the currents. The glacial till above the sandstones, though deep, is prone to erosion and slumping.

The aim was to see the Chalybeate Spring bubbling up from the Long Sands at Tynemouth. Buried under the sands there is a Lion’s Head fountain from which the iron and mineral rich waters of the Engine Well poured. It was a health attraction during the 19th Century when spas were in vogue.

Reference: Northumbrian Rocks and Landscape, Edited by Colin Scrutton.