518 Notices of Memoirs — S. Miller — Old Coast-lines of Norway. 



gravity about 6*3 ; Venus is about the same as the Earth ; and Mars 

 somewhat less. All these specific gravities are perfectly consistent 

 Vfith such an origin. The others are very much lighter, ranging 

 down to Saturn with a specific gravity of about 0-7. But high 

 temperature and gaseous envelopes may have much to do with these 

 apparent low densities : a cloudy envelope which shoald extend to 

 one-fourth of the radius would halve the estimate of density. The 

 fact that seems most seriously discordant with the hypothesis is the 

 low specific gravity of the Moon, which is estimated at only 3 5. 

 But this at any rate is about the specific gravity of the " stony " 

 group of meteorites. And we may compare the fact that the super- 

 ficial crust of the earth, and also some meteoric constituents, have 

 lower specific gravities still. We naturally expect the lightest con- 

 stituents on the surface of a planet, and a satellite may have affinity 

 with the crust. 



The conclusion then is that on the hypothesis that the Earth has 

 assumed its present condition either by aggregation or solidification, 

 out of matters previously existing within the solar system, it is 

 probable that its nucleus will be largely composed of metallic 

 materials. But since all the meteorites known would together 

 scarcely load a barge, this conclusion must be admitted to rest on a 

 very slender basis. 



III. — Some Eesults of a Detailed Survey of the Old Coast-lines 



NEAR TrONDHJEM, NoRWAT. 

 By Hugh Millbe, F.G.S., H.M. Geological Survey. 



DUEING a short visit to Norway in October, 1884, it appeared to 

 the author that the best way to help to a solution the vexed 

 questions connected with the coast- terracing of Norway was to 

 execute a careful survey of a few square miles of some suitable 

 coast region upon a sufficiently large scale. The neighbourhood of 

 Trondhjem is remarkably well suited to this purpose. The map 

 employed was partly a municipal chart on the scale of xwoo, and 

 partly an enlargement of the Ordnance Map. The limit oif all the 

 terraces and marine deposits is the famous " strand line " west of 

 the town, a double range of old coast-clifi" cut in the rock of the 

 mountain-side. Its upper line is 580 feet above the sea, and answers 

 to the " marine limit " over Norway generally. Numbers of level 

 terrace-lines have been incised — chiefly in greenish clays, like brick- 

 clays — all along the arable slopes east of the town between this 

 rock-terrace and the sea. Above the Bay of Leangen, two miles 

 east of town and river, and far beyond all erosive influence of the 

 latter, thirty of these lines were mapped one above another in the 

 first 300 feet of ascent, a distance of one mile and a half. Many of 

 these are small but extremely distinct, the earthy clays being well 

 suited to retain sharp impressions of successive sea-margins, which 

 these unequivocally are. The present coast-line, neatly etched out 

 by the waves in Trondhjem and Leangen bays, is the key to these 

 tiers of older ones. It also resembles them in havins: made little or 



