2710 J. EB. Marr—Origin of Archean Rocks. 
The difficulties above considered are suggested, if the marine 
origin of the Archean rocks be adopted ; but if they were formed on 
land, the difficulties disappear, and the feasible way of accumulating 
such rocks on land is by volcanic action. 
The researches of Prof. George Darwin upon the tides, and the 
geological bearings of his investigations, have been singularly little 
heeded by seolovists, who are apparently content with the proofs 
that the earliest fossiliferous rocks present the appearance of having 
been accumulated under tranquil conditions similar to those now 
obtaining in our oceans, and ignore the fact that the reverse appears 
to be the case when we examine the Archean rocks, and that a 
strict comparison betwixt these and the ordinary rocks cannot be 
successfully established. 
Let us consider the changes which might take place after the 
separation of the moon. 
1. Prof. Darwin, I believe, considers that a scar would be left 
where the mass which formed the moon separated from the earth, 
which might still be occupied by part of our oceans; he also says 
(Proc. Roy. Soc. vol. xxvii. p. 196), that wrinkles running in a 
general north and south direction might be raised in the earliest 
stages after separation, by disturbing force, and he points out that 
the present continents or large wrinkles conform more or less to this 
law, and adds, “it must be supposed that the general direction of 
the existing continents has lasted through geological history,” a sup- 
position to which the marine origin of the Archean rocks is, as 
already explained, opposed. 
2. Prof. Ball (“A Glimpse through the Corridors of Time,’’) 
considers that the water condensed upon the earth after the separa- 
tion of the moon’s mass. It would occupy the scar left by the 
separation, and perhaps parts of the depressions, forming somewhat 
small primeval oceans. The pressure caused by the watery atmo- 
sphere before its condensation would be, as Mr. Fisher states in his 
“‘Physics of the Harth’s Crust,” very great; consequently, when this 
pressure was removed by condensation, there would be removed an 
obstacle to the outburst of vulcanicity. There would be, therefore, 
a tendency to volcanic activity of considerable, and perhaps paroxys- 
mal violence. (The occurrence of such paroxysmal eruptions at _ 
some period or other in the moon itself is worthy of recollection in 
connexion with this.) If the outbursts were paroxysmal, the result 
would be the production rather of pyroclastic rocks than of lava- 
flows, and these pyroclastic rocks would not necessarily be coarse 
because of the violence of the action, for we know that during 
violent outbursts many of the fragments fall back into the crater, 
and are thrown out again and again, until at last they are reduced to 
an exceedingly fine state of division (Cf. Judd, ‘‘ Volcanoes,” p. 174). 
In this way the fine false-bedding described by Dr. Sorby and more 
recently by Prof. Bonney as occurring in these rocks might be pro- 
duced, just as similar false-bedding is found in pyroclastic rocks at 
the present day, and in many ancient volcanoes. A peculiarity of 
the Archean rocks noticed by Dr. A. Geikie (‘Text-Book of Geology, 
