自然历史博物馆城市自然项目之进化时间轴打造

Szerelmey’s Geological Craftsmanship: Shaping the Evolution Timeline at the Natural History Museum

The realization of the Urban Nature Project at the Natural History Museum has been the culmination of many years of planning and development and has been an outstanding achievement by all parties involved.

Our first association with the project was in February 2020, when we learnt about the project details, and most specifically, the Evolution Timeline supported by the Evolution Education Trust, featuring an epic rock canyon.

The Museum’s project has transformed the five acres of land wrapping around its building into an astonishing showcase for nature and biodiversity, as well as creating an immersive timeline

of plants, geology, and gleaming representations of reptiles, birds and mammals.

This included the creation of carefully curated landscapes with plants and rocks reflecting different geological periods through time.

We were involved in a number of different aspects of the project including external cladding to a new Nature Activity Centre supported by Amazon Web Services and a new Garden Kitchen building, using the British stones Purbeck Spangle, Ancaster White and Clipsham, installation of a number of “specimen” stones, “Rockviewers”, specially inlaid boulders and boulders for seating.

However, it was the creation of the rock canyon within the Evolution Timeline that was the most challenging and fascinating to be involved with – the two parallel walls that lead from the

South Kensington subway into the Evolution Garden on the east side of the gardens. They are the start of the immersive timeline that traces Earth’s different geological ages as well as the evolution of life. The canyon walls are a nod the Precambrian period, strongly tactile and composed of at least 26 different types of rock, including 2.7 billion year-old Lewisian Gneiss. Across the Evolution Garden, all but two rocks were sourced from across England, Scotland, Northern Ireland and Wales.

The timeline was designed to reflect geological change over vast periods of time. Once you emerge from the rock canyon, from the Cambrian period around 540 million years ago to modern day, the timeline is scaled so that each metre walked represents 5 million years.

The canyon walls posed two key challenges. Firstly, where to find the different rocks given most of the quarries closed many years ago, and secondly, how to actually build this structure to make it look authentic and capture the aesthetics and ideology of the architect and museum. The first part was eased by the help of CED Stone. Led by Giles Heap, Managing Director, they spent some considerable time sourcing a number of the more obscure stones for us. During the course of this CED Stone and Szerelmey, Dr Paul Kenrick a Principal Researcher at the Museum, and the architect engaged in quite a few scouting trips to view various lumps of rock in the far flung reaches of the UK (see article Journey Through Time in the Evolution Garden for details on the rock sourcing). CED Stone provided Szerelmey with the sawn edges of various boulders, which were delivered to our workshops, where we were able to cut them to the required shape and size.

This leads us to the second challenge, how to build the structure and present the different stones in the best way possible to achieve the client’s vision. Dr Paul Kenrick worked closely with the team on the scientific accuracy of the timeline, including its geology. The architect provided drawings for the two canyon walls, with drafted in locations for the different rocks. These were to be aligned in diagonal “seams” to replicate how rock beds naturally develop through time. The stones need to be organised from the very oldest at the mouth of the canyon to the youngest at the ends spilling into the Evolution Garden. Requirements were for the rock faces to appear rough-hewn and natural, whilst also fitting together perfectly. Additionally, we had to ensure that there were no sharp or dangerous edges and no holes. It all sounds straight forward but the planning and careful cutting of the different rocks was incredibly complicated, added to which the pieces are all extremely large and heavy making precision handling more difficult.

To start with the scants from the outside of the stone blocks were delivered to our workshop and were digitally photographed. The photographs were inserted onto the detailed drawings that we had produced from the architects’ original drawings for the wall and arranged to fit into the zone that was set aside for each stone. From this digital arrangement we worked out how much needed to be cut from the edge of each stone so that it could fit into the wall. The stones were cut to the correct size in our workshop and once each section was complete it was shipped to site to be fitted into position.

The concrete retaining walls were constructed prior to our start on site. The face of the walls were sloped backwards at between 80 and 85 degrees with the slope varying depending on the curve in plan of the wall at any point. The stones were installed from the ground up and the rear of the stones bedded into mortar. Additionally, they were restrained in position by stainless steel cramps, which were anchored into the concrete retaining wall. The stones were all lifted into position using a pick and carry crane with weights of individual pieces varying between 200kg and 700 kg. Once we had placed the stones and secured them in position, all the joints in between them were grouted. Finally, the pieces were finished by hand to reduce any areas where there were oversized areas of stepping out to the stone surface.