Developer blog for the Holocene section, which aims to explore likely changes in the local sound environment since the end of the last glacial period 12,000 years ago.

11 NOVEMBER 2012

First steps towards a timeline

A simple-but-useful timeline can be made by displaying climate data with stratigraphic and archaeological periods.

THE HOLOCENE SOUND project aims to describe likely changes in the local auditory environment across time and space. In practical terms, this means being able to say something informative about how Piccadilly might have sounded two hundred years ago, or Bermondsey 7,000 years ago.

More is known about local conditions the nearer we get to the present day, so the resolution with which we can pinpoint the where and when of sound will also increase. But this doesn’t mean that nothing useful can be inferred about eras before recorded history. Both maps and timelines can be informed by data from climate studies, archaeology, pollen remains, variations in soil type, changes in sea level and much else.

Below is a diagram representing a first step towards a timeline.

Greenland ice-core data with British stratigraphic and archaeological timelines

The graph line shows temperature proxy data taken from Greenland ice-cores. The ratio of two oxygen isotopes, O-18 and O-16, which are present in the cores allows past temperatures to be determined, and they give us some idea about conditions in the Northern Hemipshere as a whole. (For a recent critique, see the paper by Liu et al., 2012.)

The big climate events of the past 20,000 extend from the Last Glacial Maximum, when a single British-Irish ice sheet extended to the Welsh borders, curving northwards across the Pennines before descending again to where the Wash is today.

After this comes an oscillation between warm and cold conditions known in the British context as the Windermere interstadial. Then there is the rapid onset, perhaps noticeable during a single human lifetime, of a severe cold period known as the Younger Dryas, during which glaciers reappeared in the Scottish Highlands.

The Holocene epoch begins as temperatures climb again. Since then they’ve been comparatively stable, allowing civilisation to develop. The blue bar includes the five Holocene stratigraphic periods of the Blytt-Sernander climate classification system. During the Pre-Boreal period, the vast steppe-tundra of Eurasia began to be colonised by pioneering tree species such as mountain birch. In the Boreal period, the climate was initially colder and drier than today with pine forests dominating.

Rainfall and temperatures, especially at higher latitudes, rose during the Atlantic phase. It was warmer than today and this period falls within another climate episode termed the Holocene Climate Optimum. The Sub-Boreal was cooler and drier than the Atlantic period, and this in turn was succeeded by the Sub-Atlantic, which extends from around 2,600 years ago to the present.

Just as many categories we use to carve up the natural world look fuzzier the more closely they’re inspected, so the start and end dates of these climate periods are partly the result of convention. This is also true for many of the archaeological periods shown in the purple bar. The change from the hunter-gathering lifestyle of the Mesolithic to the crops and livestock of the Neolithic was gradual.

The later ages of Bronze and Iron came about faster and introduced metallic sounds to the world. Roman settlement began at AD 43, and industrialisation started with the first factories around the middle of the 18th century.

At least some of this is familiar to many people, and so the simple timeline serves as a useful foundation for what follows.


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