April 1, 1904.] 



SCIENCE. 



529 



tensive. In its present attitude the region 

 is traversed by a number of southwest-flow- 

 ing streams, running in broad, deep, rock- 

 sided valleys. These valleys are older than 

 the ice sheet which made the grooves on the 

 bed-rock, and there is internal evidence to 

 show that the amount of glacial erosion 

 within the area has been very slight. The 

 maturity of form, and the adjustments of 

 these valleys, where they are not submerged 

 beneath the waters of the present lake or 

 obscured by morainic deposits, are regarded 

 as indicating that they were eroded by the 

 pregiacial predecessors of the streams 

 which flow in them. The form and adjust- 

 ments of the valleys of the partly sub- 

 merged portions of the limestone areas, 

 particularly the Bay of Quinte and the 

 present St. Lawrence outlet, suggest that 

 these also are similar to those unsubmerged 

 valleys which can be more readily and 

 easily studied. It is concluded that these 

 rock-sided valleys formed part of a now 

 dismembered river system whose original 

 general direction of flow was southwest; 

 that the Trent River system occupies parts 

 of no less than twenty of the tributary 

 valleys of this system ; and that the present 

 St. Lawrence outlet from Lake Ontario, 

 west of the Frontenac axis, consists of a 

 complex of three of these ancient valleys 

 in which the water is now flowing in a con- 

 trary direction to that in which it was flow- 

 ing when the vallej^s were carved. 



Postglacial Changes of Attitude in the 



Italian and Siviss Lakes: Prank Btjrs- 



LEY Taylor. (Read by title.) 



In the summer of 1894 the writer spent 



two weeks in exploring the shores of the 



lakes of northern Italy for evidences of 



change in the relative attitude of the lakes 



and the land. On Lakes Maggiore and 



Como no certain evidence of wave action 



was found above present lake level. Bizt 



a study of the old deltas of the numeroiis 



torrents which descend from the mountains 

 shows that the lakes formerly stood in dif- 

 ferent attitudes, with reference to the land, 

 from those in which they stand to-day ; and 

 Lake Maggiore stood at a slightly higher 

 level. The old deltas are fragmentary, but 

 their form and structure show the former 

 lake level with approximate accuracy. 

 Since the change of attitude the streams 

 have cut down to the present level and 

 some of the larger torrents have well- 

 formed valley terraces connecting with 

 their old deltas and standing high above 

 their modern floods. In the northern part 

 of Lake Maggiore fine examples may be 

 seen at Macagno on the east side and at 

 Conobbio on the west. The valley terrace 

 back of Conobbio is a well-marked feature. 

 At Arona and Meina near the south end, 

 the old lake level was nearly 20 feet above 

 the present level, and it rises gradually to 

 50 or 55 feet near Locarno at the extreme 

 north. The Ticino River below Lake Mag- 

 giore seems to have cut down the morainic 

 barrier nearly 20 feet since the change of 

 attitude. On Lake Como the old lake level 

 at Cernobbio on the west side near the 

 south end appears to be about the same as 

 the present level and rises northward to 

 30 or 35 feet at Gravedona. On Lake 

 Garda, along the western side of the south- 

 ern part, a small but well-defined wave-cut 

 beach was found descending from the east- 

 ern end of the peninsula southeast of Salo, 

 where it is about 15 feet above the present 

 lake level, very nearly to the present level 

 at Desenzano. It is also well shown on the 

 outer end of the peninsula near Sermione 

 and on Isola di S. Biagio and other small 

 islands. The east side of the expanded 

 portion of the lake was not explored. In 

 the narrower northern part there are deltas 

 near Riva like those of Lake Maggiore, and 

 a few also along the eastern side. These 

 seem to indicate a former lake level at the 

 north end 30 or 35 feet higher than the 



