IN THE CHALK WOLDS OF LINCOLNSHIRE. 165 
out beyond the point where the two older valleys united. This 
second cut is not nearly so deep or so striking as the first, but has 
the same trench-like character, and is about half a mile long, emerging 
at last into the old pre-existent valley at the village of Hatcliffe. 
Hence its course coincides with that of the ancient valley for the 
distance of about a mile, the stream flowing to the N.H. through a flat 
alluvial level, which is underlain and flanked by Boulder-clay. At 
the end of this reach the hollow of the ancient valley turns abruptly 
to the N.N.W.; but the modern stream continues its north-easterly 
course directly through the opposing Chalk ridge, forming a third 
ravine precisely like the others, only less winding, and witha length of 
nearly halfa mile. Kmerging from this at Hatcliffe Mill, the stream 
pursues a tame and unimpeded coursethrough the undulating plain of 
Boulder-clay which intervenes between the Chalk Wolds and the 
marsh land of the seaboard. 
We have now described three out of the four Postglacial valleys near 
Hatcliffe. The fourth is in connexion with another ancient valley 
tributary to that above mentioned, and coming down from Wold 
Newton and Ravendale to join the former near the old Manor House 
five furlongs below Hatcliffe. This also is filled with Boulder-clay 
trom end to end: but in its case the Postglacial beck has been able 
to re-excavate a channel through the Boulder-clay which occupies 
its ancient valley. There is proof, however, that it was not able to 
effect this completely in the first instance ; for at a point about three 
furlongs N.W. of the ruins of West Ravendale church the Chalk 
hills forming the west side of the valley are breached by just such 
another ravine as those above described. Its course is a double 
serpentine curve, its total length just half a mile, and it emerges into 
the Hatcliffe valley a little south of the village, the road from Raven- 
dale to Hatcliffe being conducted along its bottom. 
It seems clear therefore that at one epoch during the Postglacial 
erosion the Ravendale brook ran through this ravine, but was 
subsequently enabled to revert to the course of the pre-existent 
valley. In this it was doubtless assisted by the action of the rain 
draining off the steep slopes on either side of the old valley north of 
West Ravendale; the eastern side of this part of the valley seems to 
have been the steeper, and the junction of Chalk and Boulder-clay, 
where the latter was banked up against the former, would become a 
line of least resistance along which the rivulet resulting from the rain- 
drainage would naturally take its course; the channel thus com- 
menced would be deepened until in some time of flood the Ravendale 
Beck was directed into it. ‘This course once taken would be main- 
tained, and the brook now runs at the foot of the steep Chalk bank 
with a Boulder-clay slope on the western side. 
Conclusion.—A few words in conclusion are needful to explain 
the conditions under which the brooks seem to have acted; and in 
order to picture these, it is not necessary to subscribe to any theory 
of the originof Boulder-clays. We have only to accept their existence, 
and the mapping of the country proves that, whether formed by land- 
ice or shore-ice, the Red and Purple Clays were banked up in mass 
against the eastern edge of the Wolds and spread over their eastern 
