Geology Site Account

Site name: Nazeing Gravel Pits

Grid reference: TL 385 072

Brief description of site:

The former gravel pits at Nazeing provided numerous fossils during their working lives such as the bones of mammoth, woolly rhinoceros and reindeer. The most interesting were the peat rafts within the gravels known as the Lea Valley Arctic Bed containing a distinctive tundra steppe vegetation which was the main diet of the woolly mammoth. However, of particular scientific importance were a series of organic deposits occupying a channel cut in the gravels by a former course of the river. These deposits contained fossil plant remains that bridged the time gap between the Arctic Bed and the modern Post-Glacial vegetational sequence.

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Details

The gravel pits at Nazeing in the Lea Valley worked gravels that were deposited during a cold period of the last glacial stage. In these gravels the bones of mammoth and reindeer were dredged from below the water level in the pits. Of particular interest, however was the discovery of masses of peat from what is known as the Lea Valley Arctic Bed, previously found at Ponders End, near Enfield. This bed contained plant species which provided a glimpse of the treeless, tundra landscape in Essex in the most recent glacial stage (the Devensian) about 28,000 years ago (see below).

Also at Nazeing, the pits on Nazeing Mead cut through a channel, known as the Nazeing channel which was carved by a previous course of the river and was now filled with organic sediments containing a wealth of plant fossils. These sediments were of special importance in bridging the time gap between the Arctic Bed and the established Post-Glacial vegetational and climatic sequence. A scientific paper on this discovery was published in the Philosophical Transactions of the Royal Society (Allison et al. 1952).

The pits at Nazeing Mead are now flooded and used as boating lakes. Several of the fossils, such as mammoth teeth, are preserved in the collections of Harlow Museum but unfortunately are not on public display.

The Lea Valley Arctic Bed

At the beginning of the 20th century, Essex amateur geologist Samuel Hazzledine Warren was collecting Ice Age fossil mammal bones from gravel pits in the terrace gravels of the River Lea at Ponders End, just over the Essex border, near Enfield. The fossils included bones of mammoth, woolly rhinoceros, reindeer and arctic lemming and dated from the most recent glacial stage (the Devensian), a time of extreme cold. Of most interest, however, was Warrens discovery of peat rafts sandwiched between layers of gravel which were found to contain cold climate or full glacial plants assemblages and referred to collectively as the Lea Valley Arctic Bed. So unusual and important was this discovery that this period of the Ice age has been referred to as the Ponders End Stage.

The Arctic Bed was carbon-dated to approximately 28,000 years ago, a time when, at its maximum extent, the ice sheet reached as far south as Norfolk. The bed contained a distinctive vegetation which has no precise modern equivalent. Known as tundra steppe this grassy vegetation covered much of Europe, northern Asia and North America during the Devensian stage (100,000 to 10,000 years ago) and was the main habitat and diet of the woolly mammoth. The plants of this dry grassland were faster growing and more abundant than todays tundra plants and in addition to various species of grasses they included sedges, small shrubs and many herbaceous plants. Large areas of the landscape were treeless but dwarf birch and willow, and other trees such as larch, occurred locally.

The former gravel pit at Nazeing showing a cross section through the channel at its deepest point. The channel yielded an important assemblage of late glacial fossil plants. Samuel Hazzledine Warren is shown holding a 3 metre staff. Photo © The Royal Society (Allison et al. 1952).