626 PROCEEDINGS OF THE BALTIMORE MEETING 



Introduction 



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The landslide in question occurred at the shale brick plant of the Cleveland 

 Brick and Clay Company, situated in Mill Creek valley, in the portion 

 Cleveland, Ohio, called Newburg. The writer is indebted for much informa- 

 tion to the officers of the brick company. 



Geology of the Region 



The company mentioned above obtains its shale from the cliff which forms 

 the southeast valley wall of Mill creek. This cliff is 112 feet high, and at the 

 surface consists of about 3 feet of glacial drift. This is followed by 2 to 3 

 feet of blue shale, which probably belongs to the Bedford of the Lower Car- 

 boniferous. This blue Bedford is succeeded by 18 to 20 feet of Cleveland, 

 which is divided into 3 layers. The uppermost is a dense black shale, followed 

 by a layer of blue shale, while the bottom layer is a massive black shale. The 

 black shales are highly bituminous. The Cleveland belongs to the uppermost 

 Devonian, and is underlain by about 88 feet of Chagrin (formerly called Erie) 

 shale, which has a blue color, and is more thinly bedded than the Cleveland. 

 The Chagrin is also Upper Devonian, and contains 2 or 3 sandstone layers, 

 having a maximum thickness of about 10 to 15 inches. 



Both Cleveland and Chagrin shales are jointed with greater or less regu- 

 larity, although with one exception the surfaces are not large. The Cleveland 

 shows the jointing better than the Chagrin and breaks up into rectangular 

 blocks. Nevertheless, the largest joint plane of all was noticed in the Chagrin, 

 where it formed the wall of the fissure, to be described later. This surface 

 was found to be 95 feet long and 14 feet high, as far as it was exposed to 

 view. It probably extended farther, but was obscured by fallen debris. (That 

 this assumption was correct is proven by a photograph taken at a later date 

 and shown in plate 106.) 



The Landslide 



occurrence 



During the past six years the brick company has been excavating the cliff at 

 the rate of about 60,000 to 75,000 tons a year, and has made an amphitheater 

 with vertical walls immediately in the rear of the plant. As the concave west 

 wall of this excavation curves into the valley, it is cut into on its opposite side 

 by Mill creek. Thus the operations of the brick company on one hand and the 

 stream on the other have carved the valley wall into a rounded point made by 

 two concave curves. This rounded point was the scene of the landslip, which 

 may be regarded as having three different stages, as follows : the formation 

 of the crack, the buckling, and the settling. 



FORMATION OF THE CRACK 



The beginning of the fissure was first observed on Monday, August 17, 1908, 

 at 3 p. m., when a workman who was drilling for a blast near the top of the 

 cliff in the Cleveland layers reported a crack 3 inches wide. The next morning 

 (Tuesday), at 4 o'clock, the cleft had attained a maximum width of 7 feet, and 

 continued to open until Wednesday, when it reached its widest dimensions, 

 which varied from 17 to 22 feet (see plate 105, figures 1 and 2). The crack 



