428 PROCEEDINGS OF OTTAWA MEETING. 



rendered this fact interesting, and some examinations of this bowlder-clay were 

 made. It is proposed to give the results of these examinations. 



Knowing thai l>r W. II. Dall had visited the island some years ago, I wrote to 

 him, after having examined the specimens, to ask whether any account of its 

 geology had been previously published, and learned that a very brief note, based 

 «m I>r Hall's observations made in 1874, had lately been printed in Bulletin No. si 

 of the U. S. Geological Survey, pages 259 260. DrDall further obligingly supplied 

 me with an early copy of this publication, but the facts now ascertained appear 

 to throw a wholly new light on the structure and geologic age of the island. 



Mr Macoun has furnished me with a very clear general description of the island, 

 based on his survey of it, which it is proposed to quote as introductory to the few 

 remarks based on my study of the specimens. lie writes : 



" Middleton island is a little over five miles in length and a mile and a quarter in breadth at its 

 southern and wider end. At its northern extremity it narrows to a low sandy point, from which a 

 spit extends northward mure than two miles. This spit- is bare at low tide. For more than ten 

 miles off the southern end breakers are to be seen at all stages of the tide, and at low tide several 

 rocks or shoals show above water. 



" \iiont the center of the west side of the island there is good anchorage; and from there to the 

 southern end there is no beach, the cliffs rising perpendicularly from the water to a height of 

 about 100 feet. From 100 to 300 yards back from the edge of the cliff the ground is level and 

 boggy, but it then rises abruptly between 25 and 40 feet. Tin-re is, in fact, here a distinct terrace 

 < ut I. aide in the material of the island, at a height of 100 feet above sea-level. The surface of the 

 island slopes gradually up from the eastern side to the high ground on the west, so that the 

 greater part of the water that falls upon the island runs off on the eastern side. Not even the 

 smallest stream is to he seen, but everywhere there is a constant trickling of water over the 

 el ills, and so soft is the material of which the island is composed, that on the eastern side it is being 

 gradually worn away and forms a steep incline from the summit to the water. 



"The cliffs on this side are from 30 to 50 feet in height, and from their summit it can be seen 

 that the rock or general material of the island extends for some distance out from the shore, the 

 slope being much less after the level of the sea is reached. 



"For about two miles along the eastern shore of the island the beach is strewn with pebbles and 

 small limestone bowlders. At the northern end and for about two miles along the northwestern 

 shore, the level rises but a few feet above the sea and the beach is composed of sand only. For 

 nearly a mile beyond this, toward the south, there are a good many bowlders along the shore, con- 

 sisting of granites, as well as black argillite. Just opposite the anchorage a hand of gravel not mere 

 than two feet in thickness was noticed running along the cliffs, and there may be more bands or 



beds of the same material elsewhere, as no special importance was attached to these at the ti 



and they were in (sequence not looked for or precisely noted, and none of the cliffs along the 



southern half of the island were seen from the water. In my notes, the material of which the 

 island appears otherwise to be entirely composed was called a soft conglomerate, and the stones 

 contained in it are often as large as the head or larger. 



"These seen along the shore appear to be derived, at least for the most part, from the wearing 

 away of the general material of the island, and vary in size from minute pebbles to large ones a 

 foot or more in diameter. This action must be very rapid, for when there is no true pebbly or 

 sandy beach, which is the case for about three miles ol the shore line, the waves wash in against 

 the actual Im^c of tl I ill-, which are in several places undercut. For about one and a half m ile- 

 al on g the middle part of (he island, on the east side, where the cliffs are from 10 to 25 feel high only, 

 there is no beach, hut the characteristic rock of the island extended here at half-tide from 10 to 20 

 yards out from the base of the cliff as a level floor. Tic sea was nearly calm at this time, but i he 



water was discolored by earthy matter for some di si a IK a' from the shore ; and when wet. along the 



edge of the sea the material is not only very slippery, but so soft that it may be rubbed away by 



id,, ham I. A I ion i two miles from the northern end of the island one of the officers of the An ut ill,, , 



Who had I n walking along the shore and had come 1" a point he COllld not pass, had climbed ill' 



ti,,. cliff by cutting places lor his feet with his knife, and when I reached this place I ascended to 



the summit of the el ill' in the same way." 



The component material of Middleton island, as represented by the specimens 

 brought back by Mr .Macoun. is. as already stated, a good typical bowlder-clay or 



