1972 - The Vasculum

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VASCULUM VOL. LVII. No. 3. 1972
project has been undertaken on the algae of streams in Upper Teesdale. The results of this project will be
published in more detail elsewhere, but we felt that a brief account here might be of some interest to local
naturalists. We felt too that it may prove an useful introduction to the following paper by Mr. J.R. Carter on
diatoms. Our note deals only with one stream on Widdybank Fell, Slapestone Sike, but many of the features
described for this stream are common to the majority of streams associated with the metamorphosed limestone
(see Johnson et al. 1971) in Upper Teesdale.
Slapestone Sike was one of the largest streams draining the metamorphosed limestone area,
running through one of the areas richest in interesting species of flowering plants. Although the lower reaches of
the stream are now drowned in the Cow Green Reservoir, about half the length of stream of special interest still
remains. In the upper reaches the stream flows over small boulders, but in the steeper reaches of the stream below
the present road (Birkdale Track) the water flows directly over the limestone. The part of the stream drowned by
the reservoir consisted of the lower part of the steep limestone slope, including several vertical waterfalls, a short
reach with boulders not unlike the present uppermost reach, and finally a long narrow meandering reach running
through the peat and with a substrate of black peaty silt.
Slapestone Sike showed very marked variations in flow during the period under study, with large
areas of the stream left dry under low flow conditions. However it seems improbable that the stream ever dries out
completely in winter.
A number of small tributaries entered Slapestone Sike, and five of these now remain above
reservoir high water mark. These varied markedly in their general characteristics, and only three (B, C, D in Table
I) are mentioned here. These three originate from springs which show signs of having been opened out during the
period when mining for lead and barytes was in progress. B is a ditch which drains into the left-hand side of the
stream above the road; C is a narrow channel entering on the right-hand side just below the road; D is a spring on
the left-hand side just above the present reservoir high-water mark. Band D always maintained a vigorous flow
even after long periods of low rainfall, but C nearly dried out on several occasions.
WATER CHEMISTRY
Some details of the chemistry of Slapestone Sike water (analysed by methods given in Holrnes et al., 1972) are
summarised in Table I. Although the values for only a single day are shown, they are nevertheless typical of those
obtained during periods of low flow. As compared with other (about 40) upland streams and rivers under study in
North-East England, the most striking features of Slapestone Sike and the other streams associated with the
metamorphosed limestone are the very low levels of Mg and K. For both elements the values for Slapestone Sike
are lower than for any other stream away from Upper Teesdale under similar conditions of low flow. There are
also some indications that the levels of combined inorganic N in Slapestone Sike are relatively low (unpublished
data).