Proceedings 329 



the work was done by hand. With such power we were only able to 

 get down to a maximum of 30 ft. As it was very hard to get the 

 rods down to this depth we supposed we had gotten into a good solid 

 foundation to support the filling. But soon the track began to settle 

 2 to 3 ft. in a night, and great cracks would appear, showing where the 

 underlying foundation had settled or slipped out. This happened 

 repeatedly and some said that the Bryn Mawr bog could never be filled, 

 but there was foundation somewhere between Minnesota and China, 

 and so we kept filling in. 



During March, 1906, four holes were sunk with a well-drilling 

 machine. Hole No. 1, as shown on the diagram, was just outside the 

 limits of the new fill and opposite the point of greatest settlement. 

 The drill was put down to a depth of 92 ft. and was still in greasy 

 clay. At this depth the drill buckled on account of the lateral 

 pressure from the entire ground moving toward the north. Hole 

 No. 2 was sunk outside the fill in the same manner, and at a depth 

 of 62 ft, we ran into a gravel stratum underlying the clay, and in this 

 gravel we struck a flowing well. Hole No. 3 was sunk to a depth of 

 58 ft., when we encountered gravel and a flowing well. Hole No. 4 

 was sunk through the new fill at about the point of greatest settle- 

 ment. At a depth of 71 ft. the drill was still in our new gravel filling. 

 As the grade of the new fill was only 12 ft. above the natural surface 

 of the ground this showed that the settlement at that point was 58 ft, 

 or, in other words, that the original material had been shoved out 

 ahead of the filling to the depth of 58 ft. The settlement, however, 

 did not stop at this point, for it was necessary several times after- 

 wards to raise the fill to keep the embankment up to the established 

 grade. Thus I estimate that the total settlement was from 80 to 90 

 ft. At this depth a firm bottom was evidently found, for, although 

 there has been a little settlement since, I think this is more from the 

 material packing, as is experienced in all new fills during the fall and 

 winter. 



Thus the filling stopped July 20, 1906, nearly 11 months after it 

 was begun, and, instead of the estimated material of 211,000 cubic 

 yards, it required about 500,000 cubic yards. The greasy clay in 

 the bog, which slid or v/as pushed out ahead of the gravel filling, 

 raised up a crescent-shaped tract of several acres to the north of the 

 tracks, towards Laurel Avenue, to about 20 ft. higher than its natural 

 bog level, seaming it with great cracks several feet wide and deep. 



After many questions and much examination of Mr. Jackson's 

 plan and fine series of photographs Mr. Winchell followed at 8:50 

 with "A Review of the GjBology of the Bassett's Creek Valley," of 

 which the following are the notes: This Bryn Mawr marsh or bog 

 is only part of the large region like the Mississippi' gorge below the 

 falls. The speaker was first attracted to the subject in 1876, as 

 State Geologist. The gorge between here and Fort Snelling was dif- 

 ferent from that above and below the city. He found the Bassett's 

 gorge went through the chain of lakes (Isles, Cedar, Calhoun, and 

 Harriet) and thence, in some unknown way, into the Minnesota river. 

 Bassett's creek flows over the morainic drift and strikes the surface 

 materials of the old gorge about Inglewood springs. The Glenwood- 



