Weekly Photo Challenge – Delta – Seafield Castle Beach

Seafield Castle - Lower Limestone Formation Delta Deposits 1

For this weeks WordPress Photographic Challenge, I’m taking the word ‘Delta’ literally. My six photos show just a wee bit of a massive deltaic sequence, bigger than the Mississippi delta in the southern US, and also a fair bit older too. I took these photos on the southern coastline of Fife (you can just see Kirkcaldy in the background of the first two).

This series of beds (Carboniferous in age 360 to 299 million years ago), not only covered a fair chunk of Scotland and Northern England, but they also stetched from North America, through to Germany and beyond (what must be remembered, however, is that the Atlantic Ocean didn’t exist back then, and all the continents were much closer together – this was used as evidence for plate tectonics and continental drift).

The first photo shows a small channel deposit, of relatively coarse sandstone, cutting through the finer silts and muds that make up previous overbank deposits. You can actually see the shape of the channel in this and the featured image photo!

Seafield Castle - Lower Limestone Formation Delta Deposits 2
Seafield Castle – Lower Limestone Formation Delta Deposits 2

These deposits make up part of the Lower Limestone Formation – which consist of sedimentary rock cycles, which formed local environments dominated by swamps, estuaries and deltas.

The third photo (unfortunately not a very good photo – I took these on a small compact camera 6 years ago), shows some cross bedding (evidence of a river deposit) which can be seen in the side of the channel deposit.

Seafield Castle - Lower Limestone Formation Delta Deposits - cross bedded sandstones
Seafield Castle – Lower Limestone Formation Delta Deposits – cross bedded sandstones

The fourth and fifth photos show the underlying finer silts and muds of the previously deposited overbank deposits, you can see evidence of wood fragments and rootlets.

Seafield Castle - Lower Limestone Formation - Overbank Delta Deposits
Seafield Castle – Lower Limestone Formation – Overbank Delta Deposits

 

Seafield Castle - Lower Limestone Formation - Overbank Delta Deposits
Seafield Castle – Lower Limestone Formation – Overbank Delta Deposits

The final image shows scour marks (caused by pebbles being pushed along the base of the river channel, and leaving scour marks).

Seafield Castle - Lower Limestone Formation - Scour Marks
Seafield Castle – Lower Limestone Formation – Scour Marks

The bulk of a deltaic deposit consists of the much finer grained material of the overbank deposits, but every once in a while, a river channel cuts through, representing a complete ‘change’ in the type of material deposited, ie coarser sandstones. It’s these sandstones, that act as reservoirs for any oil and gas that may have been produced in the organic rich surrounding muds.

 

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8 thoughts on “Weekly Photo Challenge – Delta – Seafield Castle Beach

  1. What a great geology lesson, complete with beautiful pictures! I really like how you used the coin to show the relative size and scale of these rock features. I have to remember that. Thanks!

    Liked by 1 person

    1. Thank you Linda 🙂 Glad you like the use of the coin as a scale, I should do it with more of my geological photos, or at least use a lens cap – I often remeber once I’ve downloaded the photos onto the pc! Lol! 🙂

      Liked by 1 person

    1. Thanks Meg, and yes, almost all rocks have some amazing stories behind them 🙂 It’s amazing to imagine that at the point when these rocks were initially formed, dinosaurs had not yet evolved, but dragonflies existed, with 2 foot long wingspans!!!

      Liked by 1 person

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