LANDSLIDE AT CLEVELAND, OHIO 631 



on the Grand river, about 2 miles southeast of Brantford, Ontario. The bank 

 was 90 feet high, and at the top was composed of 20 feet of thinly bedded 

 sandy Saugeen clay, while the remainder consisted of Erie clay, which was 

 also finely stratified. "Owing to the forward movement and reaction, the 

 deposits of the Erie clay have been raised into perfectly truncated anticlinal 

 folds, which are composed of vertical strata more or less twisted." These 

 "truncated anticlines" were probably due to vertical jointing in a very thick 

 mass with considerable lateral displacement. The behavior of the layers of 

 Erie clay seems similar to that of two blocks of wood of equal length made 

 into a horizontal column which is free to "fail" upwards. A heavy horizontal 

 thrust applied with enough eccentricity to produce failure will make the 

 blocks fly upward at the center and show the end of the grain, and would 

 therefore resemble a truncated anticline. It would seem to the writer that 

 the Brantford slide does not show the same type of thrusting as that of the 

 Cleveland occurrence, which did not have as much lateral translation. 



Dr G. B. Richardson called my attention to a paper read at the Rochester 

 meeting in 1902 by T. C. Hopkins and Martin Smallwood." However, there 

 was nothing published but an abstract, which read as follows : "A number of 

 unique folds occur in several small and rather deep ravines in the vicinity of 

 Meadville, Pennsylvania. They are limited in extent, both vertical and linear, 

 and so far as known occur only in the bottom of ravines. The relation of the 

 folds to certain landslip terraces suggests a cause for these folds." This 

 abstract seemed to deal with phenomena so similar to the Cleveland landslide 

 that the author wrote to Professor Hopkins to inquire if anything further had 

 been published on the subject, and has just received a copy of the original 

 paper. 4 The rocks are sandy shales belonging to the Cuyahoga stage of the 

 Lower Carboniferous, and there are several folds exposed in four different 

 ravines. In every case where anticlines occur they are found to be in prox- 

 imity to what Dr G. K. Gilbert calls landslide terraces. 5 



The conclusion of the paper is as follows : "In view of the conditions as 

 described above, the writers conclude that the small folds in the ravines in 

 the vicinity of Meadville are caused partly if not wholly by landslides on the 

 steep hillsides bordering the ravines." 



Conclusion 



The Cleveland landslide, which has been described in this paper, was caused 

 by a weakening of the shale rocks at the base of the cliff by various erosive 

 agents, possibly assisted by blasting. This resulted in a sinking of the outside 

 part of the valley wall, which produced a tension that caused a portion of the 

 cliff to crack off. The dislocated mass then rested on an inclined plane, so 

 that its weight had both vertical and horizontal components, which produced 

 sufficient pressure to cause the shales of the valley floor to buckle and the 

 separated block to settle on its base. In this case the vertical pressure was 



8 T. C. Hopkins and Martin Smallwood : Some anticlinal folds. Bulletin of the Geo- 

 logical Society of America, vol. 13, p. 530. 



* T. C. Hopkins and W. M. Smallwood : Discussion of the origin of some anticlinal 

 folds near Meadville, Pennsylvania. Bulletin of Syracuse University, series IV, number 

 1, p. 18. 



5 Grove Karl Gilbert : Lake Bonneville. Monograph I, U. S. Geological Survey, p. 83. 



