IN THE CHALK WOLDS OF LINCOLNSHIRE. 1638 
and the winding valley with its wooded sides sloping steeply up from 
the water, are features which one is not accustomed to associate with 
hills and valleys in Chalk districts. 
Another remarkable ravine near Louth has been formed in the same. 
way. ‘The valleys of the small becks which descend from Tathwell 
and Witheall respectively are filled with Boulder-clay *; they unite 
near Hallington, and thence the drift-filled valley continues eastward 
and leads out of the Wolds ashort distance south of Louth (see fig. 2). 
The modern stream, however, deserts this ancient valley at a point 
about three quarters of a mile E.N.H. of Hallington ; curving to the 
north and passing through a deep gorge similar to those already de- 
scribed, it joms the Ludd near Thorpe Hall, about half a mile west 
of Louth. 
The ground thus cut through by the stream is some of the highest 
near Louth, and is known as Hubbards Hill, while the depth of the 
ravine in the centre cannot be far short of 100 feet. ‘To an observer 
standing on the Boulder-clay in the continuation of the old valley, 
which is only some 20 feet above the bed of the stream, and looking 
northward into the mouth of the gorge which the stream has cut for 
itself through the chalk hills, the course of the stream seems most 
remarkable; and the origin of the ravine is utterly inexplicable 
except on the hypothesis that the pre-existent valley was once filled 
with Boulder-clay up to the level of the hill-tops, and that during 
the process of re-excavation the beck found it easier to make a 
passage northward over the Chalk than eastward through the mounds 
of Boulder-clay. 
3. Valleys near Caistor.—The third locality where similar ravines 
of Postglacial origin have been observed is the neighbourhood of 
Haitcliffe, a small village in the Wolds about 6 miles E. of Caistor. 
Here there are no less than four new cuts through the Chalk in differ- 
ent parts of one valiey-system (see plan, fig. 3). 
Fig. 3.—Plan of the valley near Hatcliffe. (Scale and shading 
as before.) 
7 
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* See map in Quart. Journ. Geol. Soc. xxxix. p. 600. 
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