29 
represented by a well marked terrace in both valleys. It is very well 
developed at the Old Golf Links on the northern side of the Swan at 
Guildford. The Guildford level is traceable almost continuously for 
a long* distance up both valleys. At Guildford it is 13 feet below 
the Gaversham level in the valley of the Swan, and seven feet below it 
in the valley of the Helena — a nice expression of the relative powers 
of the two rivers. At Albion Town north of Herne Hill it is nine 
feet below I lie Gaversham level, and at Upper Swan it is very feebly 
developed. It is here represented by obscure shoulders on the Caver- 
sliam slopes, and we estimated its depth by diagrammatic means to 
be only five feel below’ the Gaversham level. It is, however, ((idle 
traceable in the landscape. The Guildford level therefore rises towards 
the Gaversham level proceeding upstream. This is what would be 
expected during a period of stillstand, or of slow subsidence (4). 
Rejuvenating movement now supervened, and the soft Guildford 
beds became entrenched below the Guildford level, leaving it as a 
river terrace. This first phase of the rejuvenation is marked by dis- 
tinct remnants of a once continuous terrace in both valleys, but the 
new thalweg which it represents as having developed below the 
Guildford level lias been greatly obscured by the subsequent develop- 
ment of the rivers. This third level is clearly shown to the south 
of \\ est Midland railway station, in the valley of the Helena, and 
we have named it the 11 r e,sl Midland Level. At Guildford the W est 
Midland level is eight feet below the Guildford level in the Swan 
Valley, and 10 feet below it in the Helena. Again we have a response 
to steeper grade in the Helena. At Albion Town this level is 30 
feet below the Guildford level, and at Upper Swan is 34 feet below 
it. The level is easily traceable in the scenery, and we are not in 
doubt about its identification. We are here dealing with the effect 
of the steady and continuous increase in the eorrasive power of the 
Swan under the influence of rejuvenation, and as this power in- 
creases by “compound interest’’ in proceeding up a, normal stream 
Horn its month, the relative increase in eorrasive power under re- 
juvenating influences is very much greater than in the normal con- 
dition. The rule may be restated that levels due to rejuvenation will 
diverge from the older levels of stills land or su h side-nee in vrocecd- 
inrj upstream, (c.f. 4.) In other words, the further we go towards 
the head of (lie Swan, the greater will he the vertical interval between 
the Guildford and the West Midland levels (terraces). 
The West Midland level only marks a pause in the process of 
rejuvenation. When the movement started again further entrench- 
ment took place, the second pause being recorded clearly in the 
Helena but less distinetlv in the Swan valley. At Guildford, seven 
feet below the West Midland terrace, in the Helena valley, is another 
terrace which we believe records a fourth level. At the Old Golf 
Links at Guildford, in the Swan valley, is a lower platform which 
