https://wserv3.esc.cam.ac.uk/p1acollections/items/browse?tags=scree&output=atom <![CDATA[1A Collections]]> 2024-04-09T21:16:26+01:00 Omeka https://wserv3.esc.cam.ac.uk/p1acollections/items/show/19 <![CDATA[<h2><strong>L310<br /></strong></h2> <h2>Breccia</h2>]]>

Hand Specimen

Very poorly sorted.Angular to sub-angular clasts up to 30 mm long. Randomly orientated. 
Clasts mainly pale grey, some white, some red. 
Red-brown colour of the fine-grained matrix indicates iron staining. 
Matrix and some clasts fizz with acid, indicating that they are made of carbonate. This is a limestone.

Thin-section

Variety of clasts: sedimentary rock fragments, carbonate and feldspar crystals, fine-grained quartz and carbonate, some bioclasts. Clasts are quite angular.
Matrix of very fine-grained clays containing fragments of quartz and carbonate.

Rock History

Clast-supported. Clasts are angular, so sediments cannot have been transported far. (NB, if this rock were matrix supported the clasts could have been transported a long way without losing their angularity.) 
Probably scree accumulation during desert conditions, from approximately the same horizon as L326.

Advanced Notes

Iron-staining 
Hematite (Fe2O3) → red (blood-red, cherry-red, brown-red) iron-staining 
Limonite (FeO(OH)•nH2O) → yellow or brown iron-staining

The red-brown colour of this rock is probably produced by hematite.

Rock Name

breccia
]]> 2019-07-04T09:52:06+01:00

Title

L310

Breccia

Subject

Specimen Age

Permian

Location

Brockram, Cumbria

Description

Hand Specimen

Very poorly sorted.Angular to sub-angular clasts up to 30 mm long. Randomly orientated. 
Clasts mainly pale grey, some white, some red. 
Red-brown colour of the fine-grained matrix indicates iron staining. 
Matrix and some clasts fizz with acid, indicating that they are made of carbonate. This is a limestone.

Thin-section

Variety of clasts: sedimentary rock fragments, carbonate and feldspar crystals, fine-grained quartz and carbonate, some bioclasts. Clasts are quite angular.
Matrix of very fine-grained clays containing fragments of quartz and carbonate.

Rock History

Clast-supported. Clasts are angular, so sediments cannot have been transported far. (NB, if this rock were matrix supported the clasts could have been transported a long way without losing their angularity.) 
Probably scree accumulation during desert conditions, from approximately the same horizon as L326.

Advanced Notes

Iron-staining 
Hematite (Fe2O3) → red (blood-red, cherry-red, brown-red) iron-staining 
Limonite (FeO(OH)•nH2O) → yellow or brown iron-staining

The red-brown colour of this rock is probably produced by hematite.

Rock Name

breccia
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