Landline EarthCache

Landline, a sculpture by Sean Scully is located on the south side of Hanover Square. A sculpture of 5 blocks inspire by nature and stratigraphy, it certainly is a colourful piece. Let's examine the rocks used here.

Questions

Send the answers to the following questions. You can log the cache upon doing so. Quick simple answers would be sufficient.

1. Answer the following. Listing may be short but there are plenty of questions to go through.
   • From the bottom block:
     • What is the name of this rock from the 5 mentioned in the listing below?
     • What colours, apart from black, can be seen in this block? If multiple colours mention the most prominent one.
     • What shapes do most of these secondary colours appear in? What kind of sedimentary structure is it?
     • What classification of rock is this?
   • Going up the the 2nd lowest:
     • What is the name of this rock from the 5 mentioned in the listing below?
     • Look closely and you should be able to see some interesting shapes. What shapes can you see?
     • Which famous creature is this? Ammonite, belemnite, or trilobite?
     • What kind of sedimentary structure is it?
     • What classification of rock is this?
   • The middle block:
     • What is the name of this rock from the 5 mentioned in the listing below?
     • Apart from green (and any shades of green), what is the next most prominent colour?
     • Describe the shapes of this secondary colour.
     • What is the name of this shape and colour?
     • What classification of rock is this?
   • Second highest block:
     • This is nodular limestone. Observation would be tough. What type of rock is limestone?
   • Highest block - tough to observe up close so will keep it simple:
     • What is the name of this rock from the 5 mentioned in the listing below?
     • Describe the pattern of the rock?
     • Do you think this is foliation or layering/bedding? Why?
2. Which kind of rock is not present?
3. In a million years when this sculpture is compressed, what kind of rock would it be and what features would future geologists see?
4. Provide of a photo at GZ as proof of visit, as visiting the sculpture to admire the rocks is far more important than getting 100% correct answers.

Basic Rock Classification

Sedimentary rocks form through the accumulation and layering of material. Over time these materials compress and harden.

Common features:

• Layering/Bedding
• Fossils
• Sedimentary Structures

Left: Sedimentary layers. Layers accumulate and compact to form sedimentary rocks

Middle: Fossils

Right: Ripples - a type of sedimentary structure. These indicate the sediments were deposited in a fluvial environment.

Igneous rocks form from molten rock. 

Common features:

• Crystalline structure

Two examples of igneous rocks. Granite on the left, basalt on the right. Both were formed from molten lava. Note the very obvious crystals visible in the granite. The crystals of the basalt are tinier and require microscopic lens to really notice.

Metamorphic rocks form when a prexisting rock undergoes heat and pressure. A very famous example is carbon -> diamond.

• Foliation

Example of foliation in a metamorphic rock (marble).

Landline

Here are the rocks used in no particular order:

Verde Alpi – several varieties of serpentinite with the generic name ‘Verde Alpi’ are quarried in the Val D’Aosta area of the Italian and French Alps. These rocks represent ancient, Cretaceous seafloor that was obducted and emplaced as ophiolite complexes during the closure of the Tethys Ocean during the Alpine Orogeny and are to be found in the SeziaLanzo structural zone which represents the suture of the collision of the Italian microcontinent with stable Europe.

Limestone (provenance unknown) – It appears to be a rudistbearing, nodular, condensed limestone, with stylolites concentrating red-pink iron oxide minerals. It is likely to be derived from the Cretaceous limestones of either Iberia or the northern Mediterranean region.

Nero Marquina – a black limestone quarried in Marquina (Markina), Vizcaya in the Pais Basco of northern Spain. The stone is of Aptian-Albian age (Mid Cretaceous) and is a bituminous limestone with scattered white fossils of polyconitid rudist bivalves, corals, gastropods and bivalves. The stone is crossed by white calcite veins in conjugate sets

Carrara Bardiglio Marble – this is probably a dove grey variety of Italian Carrara Marble. Bardiglio grey marbles are quarried across the outcrop of the so-called Hettangian Marble of Carrara, Massa and Serravezza in the Alpi Apuane. The grey colour is imparted by very fine particles of pyrite which is disseminated through the rock.

Verona Marble – also known as ‘Rosso Ammonitico Veronese’ this is a late Bajocian – Tithonian (Upper Jurassic) condensed limestone from the Ammonitico Rosso, a nodular, red, iron oxide stained, pelagic, condensed limestone which is a prominent (but diachronous) marker horizon for Alpine geologists, stretching from Iberia to Turkey.