1908] Excursions 119 



GENERAL EXCURSION TO CHELSEA. 



The first General Excursion of the year was held on May 

 30th, to Chelsea, the most favourite resort of all. Nearly 200 

 members and friends attended the outing. President Attwood 

 was in charge and he had with him an unusually large number 

 of Leaders. After enjoying the afternoon in roaming the woods, 

 in search of specimens, or making observations on natural 

 objects, the whole party met again in the grove at 5 o'clock, 

 and listened to interesting talks l)y many of the prominent 

 members of the Club. 



Dr. H. M. Ami, who was one of the first Leaders called upon, 

 in speaking of the geology of Chelsea said, in part: "We are 

 standing on ground which is the meeting place of the two 

 extremes in the geological scale. This locality is situated where 

 the earliest rock-formations that we know of, constituting the 

 earth's crust, are in close contact with the most recently 

 deposited in the last phase of the history of this part of our 

 continent. The former consists of highly metamorphosed and 

 hard crystalline rocks, making up part of the original crust of the 

 earth; the latter, of comparativelv soft sands, gravels, clays 

 and boulder clays, constituting the soil and land surfaces 

 generally, which are tilled by the agriculturist of to-day. The 

 former holds minerals of great economic value; — mica, felspar," 

 iron ores, marbles, asbestos, graphite, molvledenite, and other 

 materials used in the arts and manufactures, not to speak of 

 rocks, such as granite, gnei&s, dolomite, etc. The older rocks 

 are ascribed to the Laurentian and Huronian systems in 

 geology, whilst the more recent ones are referred to the Pleis- 

 tocene or Post-Tertiary (sometimes called the Quarternary) 

 system. Chelsea Station stands on the edge of a terrace, or 

 old sea beach, estimated at 365 feet above present tide level (the 

 datum point) on the St. Lawrence at Three Rivers. Salt water 

 shells, well known as living or recent species in the salt waters 

 of the Gulf and River St. Lawrence below the Island of Orleans, 

 were obtained in a gravel pit a few hundred yards north of 

 Chelsea Station and are exhibited as evidence of the marine 

 origin of the sands and clays from which they were obtained. 

 Scratched pebbles (glaciated) of the district, revealed the 

 presence of a sheet, or mantle of 'till,' laid down by the Labra- 

 dorean glacier. It was a land ice-mass, possibly two or three 

 thousand feet in thickness at the maximum period of refrigera- 

 tion of this part of the continent and no organic remains have 

 been detected in the Labrador formation which constitutes 

 the lowest of the three series forming the Pleistocene system as 

 developed at this locality." 



