Stopping for a Breccia whilst passing Usher Hall? EarthCache

My 2nd EarthCache. Something a bit different as this is something I've not seen covered a lot in scotland - enjoy! :)

Now, a few things before we start:

1. This an EarthCache and there is NOT a physical container here. To log this cache, you first need to visit the location and answer the questions at the bottom of this page relating to the rocks you find there.
2. I accept answers for this EarthCache via email or by Private Messaging and will endeavour to reply to all queries within a few days. Please do NOT post your answers in your log, or I'll delete it. Also, answers must be submitted within 3 days of the log - no answers after 3 days will result in me deleting your log!! Pictures are completely fine in your logs though (as long as there are no spoilers) :)
3. Question 3 requires you to measure, there is a shop up the road that sells rulers, but I'll happily take a guesstimate :) (here's a handy reference to use if you only have a simple pen for the answers: a normal BIC pen lid is usually about 2 inches long, or just under that - if you have one of those, just use that as a basic reference)
4. The coordinates will take you to just OUTSIDE Usher Hall. There is no need for you to set foot inside, you just need to look at the walls outside the doorway.
5. There are 3 sets of doorways at Usher Hall (Doorway 3, which is around the corner, Doorway 2, which has the war memorial outside it, and Doorway 1, where the bus stop is right opposite it. YOU NEED TO VISIT DOORWAY 1!!!) This has the relevant samples of Breccia for this cache and the questions you need to answer.
6. Now, most importantly of all - the location you will be at can be a bit busy at times, if you get someone asking what you're doing or the police ask, it might be worth pointing out that there is no physical container there and you are just simply studying the rocks which anyone can clearly see if they're passing it.

Now, anyway to your lesson today..... :)

Breccia (noun) - a rock consisting of angular fragments of stones cemented by finer calcareous material.

Clast -a grain or fragment in sedimentary rocks, composed of either broken, older crystals and/or fragments of rock.

Breccia

Breccia is a rock formed from angular gravel and boulder-sized clasts cemented together in a matrix. The angular nature of the clasts indicates that they have not been transported very far from their source. There are several modes of formation for breccia. Some represent consolidated material accumulated on steep hill slopes or at the foot of cliffs. Cataclastic breccias are produced by the fragmentation of rocks during faulting. Volcanic breccias (agglomerates) comprise blocks of lava in an ash matrix and are the product of an explosive eruption. Hydrothermal breccias are formed when hydrothermal fluid fractures a rock mass. Impact breccias are formed when a meteor impacts the Earth's surface, fracturing rock at the site of the impact. The cement that binds the clasts in a breccia is generally one of either calcite, silica or iron oxide. The matrix can consist solely of the cementing material, but may also contain sand and / or silt sized clasts cemented together among the coarser clasts.

Fragments are angular because the Breccia forms near where the old rocks break up.

If the coarse grained are angular, the rocks are called Breccia.

If the coarse grained are rounded, the rocks are conglomerate.

What's a Sedimentary rock? Sedimentary rocks are rocks composed of sediment, and are the rocks formed by processes acting on the earth's surface. 

Sedimentary rock can be one of three types:

Clastic - rocks such as breccia, conglomerate, sandstone, siltstone and shale, which are formed from mechanical weathering debris.

Organic - rocks such as coal, dolomites, and limestone can be formed from the accumulation of plants or animal debris.

Chemical - rocks such as rock salt, iron ore, chert, flint, some dolomites as well as some limestones can form when dissolved materials precipitate from solution.

Clastic sediment and sedimentary rocks formed from them:

Gravel - conglomerate (a pebbly look)

Sand - sandstone (a sandy yellow colour)

Silt - siltstone (a greyish light green colour)

Clay - shale (a light blue colour)

Lithology - A Breccia where the clasts represent more than one rock type is termed polymictic (or petromictic). Whilst one has the clasts are of a single rock type are monomictic (or ogliomictic).

Sorting - Breccia that have a mixture of clast sizes is poorly sorted, whilst Breccia made up of the same sized clasts is well sorted.

Texture - clastic (coarse-grained).
Grain size - > 2mm; clasts easily visible to the naked eye, should be identifiable.
Hardness - variable, soft to hard, dependent on clast composition and strength of the cement.
Color - variable, dependent on clast and matrix composition.
Clasts - variable, but generally harder rock types and / or minerals dominate.
Other features - rough to touch due to angular clasts.

Clast sizes range from:

Fine  (2-6mm)

Medium (6-20mm)

Coarse (20-60mm)

Very coarse (60mm or more)

Breccia can be divided into 2 broad classes:

CLAST supported - This is where the clasts touch each other and the matrix fills the void.

MATRIX supported - This is where the clasts are not in contact and the matrix surrounds each clast.

 Additional information about Clasts:

Most sand sized clasts are made of quartz as it's more resistant to weathering than any other common minerals. Clasts ranging in the smaller size (like less than 2mm) tend to be made of clay materials.

Clasts larger than sand size (more than 2mm) are actually fragments of rock, mostly like fine grained rocks like basalt or andesite. Or if it's bigger coarse grained, then it's granite or gneiss.

Questions to answer for this EarthCache:

1. What colours are the Breccia stones you see at GZ? (Describe as many colours as you can see here, you're best to see the colours during the daytime, as you can't see all the colours at night there)

2. Colour wise, and looks wise, which of the two pics of Breccia I've added to this page closely resembles the Breccia you see at the location here?

3. (a) Looking at the bottom sections of the walls around the RIGHT HAND SIDE panel of the middle doorway in particular, describe the Breccia you see here, are the MAJORITY of the lines flowing up/down, sideways or diagonally?
   (b) How thin are the average Breccia grains you see here? What is the height and width to the nearest cm of the thickest piece of Breccia you see here?

4. Still looking at the bottom of the walls around the middle doorway, would you say it's poorly sorted or well sorted?

5. Looking at this area, what Lithology of clast composition do you see in the stone here? (to clarify, is it Clastic, Organic or Chemical?)

6. Tell me why you think this type of stone was used and not a stone like sandstone?

7. (OPTIONAL) As usual with EarthCaches, this is optional - feel free to take a picture of yourself at Usher Hall, but not any spoilers of the Breccia stones at gz :)