71 
CHAPTER VI. 
RED CRAa 
Between the Coralline Crag and the next overlying deposit 
there is a considerable break and erosion of the older strata, so 
that the Red Crag rests indifferently and irregularly on either 
Pliocene or Eocene beds, and in one place, towards its western 
limit, it even touches the Chalk. There is also at the base of 
the higher division a marked change in the lithological character 
of the Crag, for instead of soft organic limestones, we find coarse 
quartzose sand with a more littoral fauna. The climatic conditions 
had also changed, and in place of a warm sea, the mollusca point 
to cold currents, bringing Arctic species, unknown in the older 
deposits. These boreal forms become more and more abundant 
as Ave examine higher beds, till at last they give the dominant 
character to the fauna (see Plate IV). To what extent the Crag 
of Walton may fill the gap between the Coralline and the Red 
Crags is still an open question, for lithologically it is thoroughly 
Red Crag, but among the fossils there is a large proportion of 
southern species, and the Arctic forms so conspicuous in higher 
zones are almost entirely absent. 
The literature relating to the Red Crag is somewhat extensive, 
but a great portion of it has already been referred to in the 
Chapters on the Nodule Bed, and on the Coralline Crag, while the 
titles of the rest of the papers will be found in the Bibliographical 
Appendix to this volume. It therefore only remains to allude 
to such of the authors as have published important observations, 
or whose works are of historical interest.* 
The earliest scientific account of the Red Crag seems to be that 
given by S. Dale, in 1704, in his description of the cliff at 
Harwich.t This paper is especially valuable as preserving a 
record of an outlier now entirely destroyed by the sea. To the 
reprint of his paper a section of the cliff and four well-drawn 
plates of Crag fossils were added. Dale combated the opinion 
of the artificial or recent origin of this deposit, pointing out that 
similar beds occur also at Walton and Bawdsey, and that the 
common reversed Avhelk of the sands is not found living in the 
* This account of the literature relating to the Ked Crag is mainly taken from 
Mr. Whitaker’s Geology of the Country around Ipswich, &c. {Memoirs of the 
Geological Survey'), 1885. 
f Phil. vol. xxiv. (No. 291) pp. 1568, 1569. Keprinted in The History 
and Antiquities of Harwich and Dovercourt. 4to., pp. 18, 19, and Appendix. 
Edit. 2. 1732. 
