Marble Arch
Marble Arch stands at the busy northeast corner of Hyde Park, marking the intersection of Oxford Street and Park Lane. John Nash conceived it in 1827 as a triumphal gateway to the newly expanded Buckingham Palace, and Edward Blore completed the structure in white marble by 1833 before it was dismantled and reassembled at this location in 1851.
Geological Background
Marble Arch in London is clad in marble, and was the first British building to do so, making it a pioneering structure in terms of material use. Noteworthy are the eight enormous Corinthian columns that were each cut from a single slab of marble. The material of choice is Ravaccione marble, which is a grey-white variety of Carrara marble sourced from Italy. So technically, it is a type of Carrara marble, but more specifically, it's the Ravaccione variety.1
Ravaccione marble is a crystalline metamorphic rock that began life as Jurassic-age limestone deposited approximately 190 million years ago on the floor of the ancient Tethys Ocean. Tectonic forces associated with the Alpine orogeny subjected these limestones to elevated pressures and temperatures, causing recrystallisation of calcite grains into a dense mosaic of interlocking crystals. This process eradicated original bedding planes, producing a rock whose uniform texture and notable translucency under polishing are prized by sculptors and architects alike.
Although both marbles emerge from the same mountainous region of the Apuan Alps, Ravaccione and Carrara marbles differ markedly in their texture, veining, and quarrying methods. Carrara marble sensu stricto encompasses a range of commercial varieties distinguished by smoky grey veins set against a light grey to white ground and is typically extracted from open-pit quarries where daylight and weather can introduce microfractures and variation in moisture content.
In contrast, Ravaccione marble was quarried from the Galleria Ravaccione, an underground gallery carved into the heart of the Apuan Alps in northern Tuscany, Italy, between the hamlets of Ravaccione and Fantiscritti. Accessed via a 1.200-metre tunnel hewn through the mountain, the quarry's vaulted halls provide a stable temperature (18°C) and humidity, ideal for preventing stress fractures during extraction and transport. Diamond-wire saws slice massive blocks from the marble seams revealing a marble with exceptional uniformity and minimal veining, a cleaner white background and a medium to coarse grain. Artisans then polish the surfaces to evoke the stone's inherent translucency and reveal its subtle spectrum of whites and creams, and crystalline appearance.
These contrasting quarrying environments and lithologies account for Ravaccione's reputation for purity and translucency versus the broader variety and veining patterns seen in Carrara marbles. In fact, Michelangelo himself reputedly prized Ravaccione marble for its uniform grain and luminous quality, selecting blocks here around the turn of the 16th century for his finest works3.2,3,4,5
How to claim this EarthCache?
Send me the following;
1. The text "GCB96C1 Marvelous Marble Arch.
2. The answers to the following questions;
- What geological process transformed Jurassic-age limestone into Ravaccione marble, and what changes occurred during this transformation?
- How do the quarrying environments of Carrara and Ravaccione marbles influence their physical properties and appearance?
- What is the prevailing hue of the marble on the exterior archway when viewed at eye level?
- Would you characterise the marble's grain size as fine, medium, or coarse when examining a polished section up close?
3. Take a selfie (optional) and/or a photo of a thumbs-up, peace-symbol (V) or personal item, clearly showing Marble Arch and/or St. George the dragon slayer in the back, and attach it to your log.*
References
1 marble-arch.london, A closer look at Marble Arch and its sculptures (Retrieved 2025/08). 2 Wikipedia.org, Marble Arch (Retrieved 2025/08). 3 showcaves.com, Galleria Ravaccione (Retrieved 2025/08). 4 visittuscany.com, 5 marble quarries to visit in the Apuan Riviera (Retrieved 2025/08). 5 www.litosonline.com, Different varieties of marble from Carrara (Retrieved 2025/08).
* Effective immediately from 10 June 2019, photo requirements are permitted on EarthCaches. This task is not optional, it is an addition to existing logging tasks! Logs that do not meet all requirements posed will no longer be accepted.
For additional information, visit; Geosociety.org, Geocaching.com Help Center and Geocaching.com Forum.