G6 PROCEEDINGS OF WASHINGTON MEETING. 



The method which I have adopted for determining the marine boundary is as 

 follows: I first select on the topographic map hills of sufficient altitude to make it 

 certain that they were above the marine boundary under all conditions. They must 

 be mainly covered with moraine matter, in which the breakers usually leave the most 

 easily distinguished traces. The situation has to be open and the ground mod- 

 erately inclined, so as not to interfere with the action of the breakers. Finally, 

 such localities must be selected as are situated in the neighborhood of points 

 already leveled, from which I could start when ascertaining the level of the marine 

 boundary. This, in different places, is of a somewhat different appearance. At the 

 promontories it is often formed as a cut terrace with a more or less steep bluff, at 

 the base of which sometimes only the greater bowlders are left just as the bowlder 

 pavements described by Mr. Spencer, and when the erosion of the breakers has 

 been very strong the rock is laid bare up to the very uppermost marine limit. At 

 more protected points the limit is sometimes marked by built terraces and beaches. 

 In ascertaining the level of the cut terraces I have always taken that of their base, 

 while of the others that of their summit, which, in general, is a few decimeters 

 lower. In every locality the mean is taken of several points at the boundary, and 

 the probable error, I think, will hardly exceed one meter, being usually only a few 

 decimeters. Most of the points (now amounting to about 60 or 70) are determined 

 with good hand-levels, some with spirit-levels, and only two with aneroids. 



The first points which I happened to determine were situated in eastern Scania, 

 in the direction of the strike of the old deformed geoid, so that the heights of the 

 different points were nearly equal, viz, some 50 meters. Somewhat more toward 

 the south I afterward obtained successively 48, 42, 37, 32 and 21 meters, and that in 

 quite open localities, in which are found well-developed series of sea beaches below 

 the marine boundary, while immediately above the same the moraine matter does 

 not show the faintest trace of any washing by the sea. It was therefore evident 

 that it is necessary to assume an unequal uplift of the land in this the southernmost 

 part of Scandinavia. This led me to the conclusion that not only were the obser- 

 vations of Bravais in the Altenfjord correct, but that in all probability the same 

 law would be found exemplified all over the Scandinavian peninsula. In order to 

 investigate this question further, I attempted in 1SSS to plot on a map, published 

 in the Transactions of the Geological Society of Stockholm for that year, such ap- 

 proximate determinations of the upper marine deposits in the various parts of 

 Scandinavia as were available at that time. I thereupon connected the various 

 points of equal deformation by lines, as Mr. Gilbert bad already done for Lake 

 Bonneville. For the sake of brevity, I named these lines iaanabases or isobases. 



This first attempt to thus put together the facts showed already most clearly that 

 all the points could be grouped in one single system, all the higher localities appear- 

 ing in the central parts of the land and all the lower ones in the peripheral parts, 

 in the south as well as in the west, the east and the north, in such a manner that the 

 isanabases formed concentric circles. The phenomena, thus being of purely local 

 nature, can have nothing to do with general changes in the level of the sea. Fur- 

 thermore, as the highest marine deposits are situated in the central parts of the 

 land as high as 260-270 meters above the sea, it will be easily seen that the very 

 much reduced remnants of the original ice-sheet which could possibly exist when 

 the sea in late-glacial time reached so far could not — with respect to their local at- 

 traction — have played any role worth mentioning in the explanation of the raised 

 beaches ; and the more so, when the figures we get when starting in the calculation 



