Trying to make multi-layer terrain gen

Attempting to make a (top to bottom) snow -> ice -> deepslate surface terrain gen for a custom dimension but it end up looking like the picture. Relevant: json { "sea_level": -120, "disable_mob_generation": false, "ore_veins_enabled": true, "aquifers_enabled": false, "legacy_random_source": false, "default_block": { "Name": "minecraft:deepslate", "Properties": {} }, "default_fluid": { "Name": "minecraft:lava", "Properties": {} }, "spawn_target": [], "noise": { "min_y": -128, "height": 480, "size_horizontal": 4, "size_vertical": 4 }, "noise_router": { "initial_density_without_jaggedness": 4.0, "final_density": 4.0, "barrier": 1.0, "fluid_level_floodedness": 1.0, "fluid_level_spread": 0.1, "lava": 1.0, "vein_toggle": 0.5, "vein_ridged": 0.4, "vein_gap": 0.3, "temperature": -1.0, "vegetation": 0.1, "continents": 0.0, "erosion": 1.0, "depth": 0.1, "ridges": 1.0 }, "surface_rule": { "type": "sequence", "sequence": [ { "type": "condition", "if_true": { "type": "above_preliminary_surface" }, "then_run": { "type": "block", "result_state": { "Name": "minecraft:snow_block", "Properties": {} } } }, { "type": "condition", "if_true": { "type": "vertical_gradient", "random_name": "minecraft:deepslate", "false_at_and_above": 350, "true_at_and_below": 349, "anchor": 300 }, "then_run": { "type": "block", "result_state": { "Name": "minecraft:blue_ice", "Properties": {} } } }, { "type": "block", "result_state": { "Name": "minecraft:deepslate", "Properties": {} } }, ] } } Version: 1.20.4 Loader: NeoForge