Tarns of the Lake District

Tarns are situated in various different locations, both at lower level valley plains and mountainous regions of the Lake District; bygone reminders of their glacial origins. They can change form due to alluvial deposition made by the constant run off from becks (mountain streams). Over long periods of time, they can silt up the adjacent land with sand, gravel and clay, making some areas incredibly fertile, particularly those on valley floors. Many tarns are natural, a work of art in nature’s canvass, crafting and forming ever-changing scenery that will some day be unrecognisable to our present-day eyes.

There are some tarns the result of human intervention, created for our increasing need for clean drinking water, dammed and turned into reservoirs to increase capacity. More than a third, maybe even as many as 40% of the tarns in Lakeland, have probably had some form of alteration. In addition to industrial purposes, this also includes the draining of tarns to create more land for new agricultural ambitions. The more controversial interference would be our justification for aesthetics, such as that fine example seen in the Victorian landscaped Tarn Hows, near Coniston. However we look at the humble tarn, it can be difficult to define what these diverse bodies of water actually are. Ask anyone familiar with the Lake District and the chances are they would be aware of tarns and explain what one is, even if never having visited one in person. The word tarn is evocative of something that would not be out of place in Tolkien's Middle Earth. Yet what a tarn is can defy most non-academics simply because of their diversity in size, shape, form, and purpose, especially when asking: when does a tarn become a lake? This is not always directly associated with size, as some tarns are bigger than lakes. This is where things can become ambiguous and convoluted.

Cirque tarns
These are small bodies of water usually formed in mountainous hollows or corries, known also as glacial cirques. These are bowl-shaped, ice-excavated rock basins, some of which are naturally deep, once carved by millions of tonnes of ice, erosion and weather. Cirques typically have three steep sides containing a headwall and two enclosing sidewalls, with a fourth being more open where a glacial till or moraine (rock debris that formed a dam) eventually enclosed and trapped the remaining ice. Some of the best examples of a cirque tarn are Blea Water, Angle Tarn (Langdale), Stickle Tarn (below image), Blind Tarn and Scale Tarn. Water will usually flow from the moraine, ensuring the tarn maintains a fairly constant depth, and continue its journey down towards another tarn or lake via a network of becks and a river as seen at Little Langdale Tarn before eventually flowing into a larger body of water, in this case, Windermere.



The typical characteristics of cirque tarns resemble a pudding bowl, some definitely more circular than others. This bowl will have a single deep point, usually in or near the centre, some of which are very deep for their size. A prime example of this is Blea Water, just north of the Kentmere valley and west of Haweswater Reservoir. It has a depth of 63 metres (206 feet), almost twice the depth of Grisedale Tarn at 33 metres (108 feet). The next deepest is Red Tarn at 26 metres (85 feet), and Easedale Tarn at 22.5 metres (74 feet). The moraine can also affect how deep the tarn is, depending on how much debris was moved during the "ice action" of its excavation.

Cirque tarns do come in a variety of shapes and sizes, not all of these being the typical shape one would expect to see. Those that stand out, mentioned above, were formed because the land under the ice dome during the last glacial period, paired with the radial (outward) flow of ice, meant that certain geological processes made the shaping of them possible. There are upwards of 200 cirque type features, yet, one would be surprised to see that of this large number, only 19 hold water. Some cirque basins did, historically, hold water but have now either dried up, primarily due to the sedimentary infilling from the various becks that flowed into them. At the end of the last glacial period, the landscape would have looked very different, scarred, barren, devoid of life, and the number of cirque tarns would have been greater. In the last 13,000 years, these have been reduced dramatically and lost to history. Yet the evidence of infilling is still very much apparent as seen at Blind Tarn Moss near Grasmere, and at Dry Cove Moss near Weatherlam, where the outline of the cirques now reveal a peaty wetland. It is only a matter of time before the tarns will all but disappear because of the same infill process. That is, unless human intervention disrupts that natural progression.

These mountainous tarns are unlike their lower altitude relatives found in the outlying fells (and various other locations in the northwest) where they look more like large ponds. While a number of these will be natural, others will be man-made, once serving different industrial purposes.

List of tarns
Looking at the broader picture, there are over 1826 tarns and small lakes throughout the county of Cumbria, many more than could ever be listed here. Some of these are cirque tarns, immediately identifiable from their distinctive form, but generally the tarns throughout Cumbria, and more so Lakeland, have dramatically varying character, form, and function. Extensive research has shown that of this vast number, there are 364 tarns believed to be artificial: mining features, quarry ponds, reservoirs, many now disused and left to nature. Whatever your thoughts on the subject, many are, indeed, special places to explore on foot.

Etymology
The word tarn, used extensively throughout the northwest and in particular the Lake District, has Old Norse origins with an eventual and what appears to be a subtle shift into late 14 century Middle English, typically meaning a "small mountain lake". It is also a dialectal word popularised by Lakeland poets. Here, we can see the word-shift and how it developed through time:
 * Proto-Germanic ternō → a reconstructed word meaning a small lake or water hole
 * Old Norse tjörn → meaning a small mountain lake, pond or pool
 * Middle English terne (alternative tarne) → meaning a lake, pond or pool

It should also be noted that tarn is also cognate with other Scandinavian languages: Danish and Norwegian tjern (small forest or mountain lake), Faroese tjørn (pond), Icelandic tjörn (pond) and Swedish tjärn (small forest lake), all of which have the same or very similar meanings.

It seems apparent that tarn is a word synonymous with its Scandinavian origins. Norse influences dominate the very words we use today to describe the much loved places that draw hundreds of thousands of tourists each year to its Lakeland charms. Yet, this simple, unassuming word tarn occurs in over seventy names, a testament to the prevalence of an ancient language not from these shores. Whilst the definition of a tarn would typically originate from the Old Norse "small mountain lake or pool," this definition cannot stretch to every occurrence where tarn is used. Therefore, we could surmise that some tarns have been named thus in more recent times to fulfil a more general definition that suits a small lake, pond or pool without the "mountain" counterpart its lofty relatives are so uniquely associated.

Sports and recreation
Tarn swimming is also a popular sport for those with a sense of adventure willing to brave the cold waters in some of the wildest and remote locations the Lake District has to offer. One of the best tarns for swimming is Red Tarn at Helvellyn, dramatically lying at the base of the iconic Striding Edge. This tarn is home to the endangered fresh water Schelly fish, which is endemic here and at Brothers Water, Haweswater and Ullswater.