282 Mr. R. C. Taylor on the Geology of East Not folk. 



whose bed has emerged from its orijrinal level. About 150 

 square miles, or one hundred thousand acres, are occupied by 

 these valleys; and in traversing them, on the causeways by 

 which they are now intersected, one is reminded of those si- 

 milar but more extensive tracts of low lands on the opposite 

 coast. The general width of the river Yare is about 150 feet ; 

 and of the Waveney and Bure 100 feet each. In their wind- 

 ing courses they frequently expand into or communicate with 

 small lakes, locally termed Broads. There are upwards of 

 sixty of these broads; besides as many smaller pools. Their 

 depth varies from 15 to 30 feet, and they differ in extent, from 

 one acre to 1200; that of Breydon being the first, and Lake 

 Lothing the sixth in magnitude. 



It may not be irrelevant to state, that the drainage of the 

 greater portion of Norfolk and part of Suffolk, is effected by 

 means of Yarmouth haven. The summit or highest edge of 

 this area of di'ainage, extends to within seven miles of the sea 

 at Snettisham, on the opposite side of the county. Within 

 these limits is comprised an area of 1200 square miles in Nor- 

 folk, and 220 in Suffolk. Consequently, the quantity of water 

 collected in, and passing out of, so extensive a basin is consi- 

 derable. In connection with this subject is the geological fact, 

 that these limits of drainage singularly correspond with the 

 boundaries of the great deposit of clay, brick-earth and dilu- 

 vial matter, resting upon the chalk, in this portion of Norfolk. 



The most material circumstance now to be inquired into, is 

 the presumed occupation of the eastern valleys, to the height 

 of 40 feet, by marine waters, at an indefinite period, subse- 

 quent to the deluge. The authority for this supposition ap- 

 pears to be solely found in the beds of marine shells, which 

 are exposed at that elevation, along the sides of the Norwich 

 valley. These shells are described as strictly similar to those 

 of the testaceous molluscae now abounding in the adjacent sea, 

 and continually met with upon our shores. Upon this apparently 

 strict conformity to the genera of present times the conclusions 

 of Mr. Robberds are obviously founded : but I conceive, if it 

 should appear that these exuvias are more properly assignable 

 to an aera preceding the deluge which last affected our earth, 

 that gentleman will consent to abandon the views he at present 

 entertains. 



It happens that a catalogue of the stratified shells of Bra- 

 merton, the principal source in this neighbourhood, whence 

 Mr. Robberds, Mr. Sowerby, Mr. W. Smith, Mr. Leathes, and 

 others have derived their specimens, was not long since com- 

 municated by me in the Geological Society's Transactions. 

 From this list, which is capable of extension from subsequent 



discoveries 



