934 



SCIENCE 



[N. S. Vol. XXXI. No. 807 



features are farther advanced in erosional 

 development, and that at the same time the 

 depth of erosion decreases down-stream. 

 The main valley of the first cycle was here 

 widely opened; the main valley of the 

 second cycle, originally a narrow, incised 

 meandering valley, has now reached the 

 stage of nearly consumed, blunted spurs, so 

 that in this stretch the Lamone wanders 

 freely on a flood plain of greater breadth 

 than that of its meander belt. The valley 

 sides of the lateral streams are here in 

 large part already regraded with respect 

 to the new depth that the valleys have 

 gained; but in consequence of the faint 

 northeastward dip of the weak clays, the 

 higher part of the lateral valley sides are 

 often incompletely graded on the northeast- 

 ern or outcrop slope, and there exhibit a 

 minute, bad-land dissection; while the 

 southwestern or basset slope of the valley 

 sides is smoothly sloping. As the hills 

 decrease in height towards the plain of the 

 Po, the height of the terrace remnants of 

 the earlier valley floor over the newer val- 

 ley also decreases ; and the hills and the ter- 

 races vanish together at the border of the 

 fluviatile plain. All this permits one to 

 make a somewhat more definite statement 

 regarding the uplift by which the first 

 cycle of erosion was interrupted and the 

 second introduced; namely, that the uplift 

 seems to have been greater toward the 

 mountains in the background than toward 

 the plain in the foreground; hence, that it 

 apparently involved a gentle northeastward 

 tilting, such as had been inferred near 

 Ancona. But let it be added at once that 

 the geographer's interest in these infer- 

 ences as to past uplifts of the Apennines 

 does not spring from any concern on his 

 part as to past events as such, but goes only 

 so far as past events may aid him in the 

 appreciative observation and the effective 

 description of existing land forms. 



A railroad and a main highway follow 

 the western terrace remnant of the earlier 

 vaUey floor; hence they have to cross the 

 newly incised side-valleys on embankments 

 and bridges. I believe a few small villages 

 lie on the broad floor of the newer valley 

 in the outer belt of weak clays ; but in the 

 inner belt of stronger structures, all the 

 villages are on the terrace ; the newer valley 

 being too narrow for occupation. On the 

 western terrace near the junction of the 

 two belts lies the village of Brisighella; it 

 was by the chapel just above this village 

 that we spent our morning hours, sketching 

 and writing; and I can strongly recom- 

 mend this spot as the goal of a physio- 

 graphic pilgrimage for all who choose to 

 follow. 



Thus I might go on describing the 

 smooth-floored basin of Florence, in con- 

 trast to the maturely dissected basin of the 

 Val d'Arno; the young lowland and its 

 simple shoreline of elevation and prograda- 

 tion north of Leghorn, in contrast to the 

 complicated mountainoiis shoreline of the 

 Riviera Levante, with its interesting fea- 

 tures due to slight and recent uplift towards 

 Genoa, and corresponding depression to- 

 wards Spezia ; an account of this delightful 

 district was presented to the research de- 

 partment of the Royal Geographical So- 

 ciety in March, 1909 ; it has since then been 

 published in a paper on "The Systematic 

 Description of Land Forms.'" Much 

 might be said of the maturely established 

 elbow of capture of the Tanaro at Bra; 

 of the superb exhibitions of glacial erosion 

 in the overdeepened trouglis of the Alpine 

 valleys, whose terminal basins hold Lakes 

 Como and Maggiore, and of the remark- 

 able pair of glacial distributaries by which 

 the irregular intermediate basin of Lake 

 Lugano was excavated ; and so on. It was 



' Geographical Journal, September, 1909, 300- 



