This EarthCache is near to the memorial to Benjamin Waugh. He was born in Settle, and he is known as the founder of the NSPCC, the National Society for the Prevention of Cruelty to Children. He was born in Settle on February 20 1839. The memorial plaque is nearby to the EarthCache location.
The EarthCache location is shown in the below photograph.
The stone is sandstone, which is a sedimentary rock.
🤔 What is sandstone?
Sandstone is a sedimentary rock, formed by sediment which has been laid down. In the case of sandstone, the sediment is sand and gravel.
➡️ How does it form?
The formation of sandstone involves two principal stages:
🔸️Initially a layer or layers of sand accumulate as the result of sedimentation, either from water (as in a stream, lake, or sea) or from air (as in a desert). Typically, sedimentation occurs by the sand settling out from suspension; i.e., ceasing to be rolled or bounced along the bottom of a body of water or ground surface (e.g., in a desert).
In the case of this location, the sandstones were deposited in a river delta environment.
🔸️Finally, once it has accumulated, the sand becomes sandstone when it is compacted by pressure of overlying deposits and cemented by the precipitation of minerals within the pore spaces between sand grains.
The most common cementing materials are silica and calcium carbonate, which are often derived either from dissolution or from alteration of the sand after it was buried. Colours will usually be tan or yellow (from a blend of the clear quartz with the dark amber feldspar content of the sand). A predominant additional colourant is iron oxide, which imparts reddish tints ranging from pink to dark red, with additional manganese imparting a purplish hue.
This stone shows evidence of the sandstone being deposited in the form of cross bedding.
We are here to look at the cross bedding in this stone. Bedding relates to the individual layers of the rock, and we are here to look at evidence in the bedding of the deposition of sediment in a river delta environment.
Looking at the stone , you will notice lines on it, which are not all going in the same direction, and some are not horizontal. This reflects the transport of gravel and sand by water currents that flow over a sediment surface in a river channel, such as occured in the Namurian Period. This evidence is known as Cross Bedding.
🤔 The formation of Cross Bedding.
Due to the water current, also known as paleoflow, sediment is moved along with it. The sediment is moved upwards, and is eroded from a gentle upcurrent slope, it is then redeposited on a downcurrent slope, as demonstrated in the below image.
Eventually, layers of sediment build up on the downcurrent slope, and there is a build up of cross bedded layers. They are called cross bedded, as the beds go diagonally across rather than level.
The direction of the cross bedding demonstrates the direction that the sediment was deposited, and thus the direction of the flow of the paleoflow. Cross bedding can change direction, due to change in current direction, and can also cease, if there is gentle non turbulent movement of water such as in a lagoon or pond.
🤔 Trough Bedding.
Despite it being millions of years ago, it is still possible to see features from river channels preserved in the rock. If you have ever tried to cross a river, it very quickly becomes apparent that there are different depths. This can be due to troughs and channels in the river bed, and evidence of these can be preserved in the stone as Trough Bedding. Trough Bedding is basically when sediment gets deposited in troughs and channels, and they have a distinct U shape. They often are in cosets, which means multiple trough beds.
Example of Trough Bedding.
📝 This being an EarthCache, in order to log it, I ask that you answer some questions. Please send them to me, and do not include them in your log. You can send them to me by using the message facility or email, both of which can be found by looking at my profile.
1. Please describe the bedding on this stone.
2. What direction would have the paleocurrent been in order to create this cross bedding?