The Sloan Great Wall is an immense structure of galaxy superclusters spanning approximately 1.37 Gly (Gott 2005; Park 2012). Structures of this magnitude should not have had sufficient time to assemble through hierarchical gravitational clustering since the Big Bang under standard ΛCDM growth rates. The Sloan Great Wall approaches or exceeds the theoretical homogeneity scale of the cosmological principle.
The standard model assumes hierarchical gravitational structure formation with a maximum coherent-structure size below the cosmological-principle scale of roughly 300 Mpc. Sub-Gpc walls demand either non-Gaussian initial conditions or modifications to growth rates, neither of which is parsimonious within minimal ΛCDM.
SCT replaces the hot-dense-center with a superluminal collision and the thermalized debris field. From this single change, the Sloan Great Wall is one member of the cascade-deposited large-scale anomalous-structure population (P55). At its 420 Mpc characteristic scale, it corresponds to a head-on cascade collision (P33) at an intermediate cascade stage between the largest first-stage events (gigaparsec walls) and the smaller daughter-stage events (hundred-Mpc filaments).
The cascade impact-parameter distribution P(b) ∝ b combined with the cascade-stage hierarchy (P22, P34, P36, P37) produces the wall-population demographics: roughly 5 to 15 walls at hundreds of Mpc and 5 to 7 walls at gigaparsec scales per observable patch. The Sloan Great Wall sits in the upper end of the hundreds-of-Mpc population. It joins the CfA2 Great Wall (recid 93, 94), the Hercules-Corona Borealis Wall (recid 100), the Big Ring (recid 85), and the Giant Arc as members of the same M4 cascade-deposited family.
Multi-stage cascade dynamics (P36, Section D2) provides the formation context: the wall was deposited by a single intermediate-stage cascade collision rather than assembled by gravitational clustering over cosmic time. Coherence at the wall scale is achieved at deposition, not built through hierarchical assembly. The same M4 framework that produces the gigaparsec ring-and-arc structures (recid 85), the KBC supervoid (recid 86), and the cosmic-web morphology produces the Sloan Great Wall as a predicted geometric feature.
If precision Euclid + DESI cosmic-web morphology surveys find the wall-length distribution at 200 to 500 Mpc consistent with ΛCDM hierarchical-clustering Gaussian-tail expectations at the 5% level (no excess walls in this range, no discrete cascade-stage signature), the M4 cascade-collision wall explanation is refuted. The signature SCT prediction is roughly 5 to 15 walls of Sloan-comparable scale per observable patch.