1897] NOTES AND COMMENTS 295 



Esthonia seem to have been more successful than that to the Ourals, 

 owing to the difficulty of transporting the larger number in the 

 latter case. Those who visited Finland had an opportunity of test- 

 ing the classification of supposed Archaean rocks recently put forward 

 by Mr J. J. Sederholm (see Natural Science, vol. x. 1897, p. 79). 

 The general opinion seemed to be that the evidence was insufficient 

 to warrant the ascription of an Archaean age to many of the rocks. 

 Under the leadership of r>aron de Geer the glacial phenomena of 

 the district were studied, and the Asar, with which many English 

 geologists made their first acquaintance, gave rise to interesting dis- 

 cussions. The main object of the Esthonian excursion, under the 

 direction of Akademiker Friedrich von Schmidt, was the examination 

 of the Cambrian, Ordovician, and some of the Silurian rocks of the 

 Province. The junction of Ordovician and Silurian was not over 

 easy to follow under the conditions of the excursion, but the grand 

 series of absolutely unaltered Cambrian with Platysolcnites, Olencllus, 

 Obolus, and Dictyohema, was a revelation to many. The party had 

 also the advantage of the presence of A. von Mickwitz, whose palaeon- 

 tological work in these Cambrian beds has been of the highest value. 



At the Congress itself, if no practical results were arrived at, 

 still many discussions on matters of general importance to geologists 

 took place. The main problem put before the Congress was the 

 classification and nomenclature of rocks, both stratified and igneous, 

 but chiefly the former. Treatises by Messrs Freeh, Bittner, Walther, 

 and Loewinson-Lessing formed the basis of discussion: This re- 

 sulted in the following resolutions : " The Congress is of opinion 

 that the historical method of classification must be adhered to, 

 though it should continually be made more natural. The council 

 is to nominate a committee to study the principles of classification in 

 this spirit." " The introduction of a new stratigraphic term into 

 international nomenclature should be based on a clearly defined 

 scientific necessity supported by peremptory reasons. The appella- 

 tions applied to a terrane in a definite sense cannot be applied in 

 any other sense. The date of publication is to decide the priority 

 of stratigraphic names given to the same series of beds." " For the 

 minor stratigraphical divisions, sufficiently characterised palaeonto- 

 logically, in the case of the creation of new names, it is preferable to 

 take as their basis the most important palaeontological characteristics. 

 Geographical or other names should only be used for divisions of a 

 certain importance containing many palaeontological horizons, or 

 when the terrane cannot be characterised palaeontologically." "Names 

 badly formed from an etymological point of view are to be corrected 

 without excluding them from the domain of science." Certain proposals 

 of minor importance were referred to the above-mentioned committee. 



There is no doubt that with the advance of geological knowledge 



